WEBT News

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WEBT News 47 - September 17, 2007

New campaign on 3C 66A

Due to its very bright optical state, 3C 66A is the subject of a new WEBT campaign, led by Markus Böttcher.

Information and instructions can be found here .

Thank you in advance for your participation.

Massimo Villata and Markus Böttcher

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WEBT News 46 - September 4, 2007

The GASP has started

The GLAST-AGILE Support Program (GASP) of the WEBT has started to work.

Its main aim is to perform optical-to-radio long-term continuous monitoring of a list of selected gamma-ray-loud blazars during the operation of the AGILE and GLAST satellites. The corresponding light curves will be composed almost in real time (i.e. with about a weekly update), since they have also the function of an alert tool for triggering multifrequency observations.

A dozen telescopes are involved in this effort, but we expect that only a part of them will really contribute with continuous monitoring and timely data reduction in this first phase. Whoever can plan to monitor the listed sources and can provide timely good-quality data is invited to join the GASP.

Among the first results of this new WEBT observing effort, you can look at the ATel on the bright optical state of PKS 1510-08, just posted, and at the first GASP light curve of 3C 66A, showing the recent activity of this source.

All the best,

Massimo Villata

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WEBT News 45 - August 8, 2007

3C 279 campaign extended

Dear All,

concerning the campaign on the 2006-2007 outburst of 3C 279 (see the WEBT campaign page, and WEBT News 41 and 42), led by Valeri Larionov, we already have quite good coverage for the period earlier announced (April 2006 to February 2007). However, the source continued to vary until the end of its period of optical visibility (end of July), so that we invite you to send us also the data taken in March-July (or even later, in particular for radio-mm observations). The final data submission deadline is September 15.
Thank you very much for your excellent observing effort.

Valeri Larionov and Massimo Villata

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WEBT News 44 - July 19, 2007

3C 454.3 campaign extended

Dear All,

because of the current brightening of 3C 454.3 in the optical bands, the WEBT campaign on this object led by Claudia M. Raiteri, "Following the post-outburst phase of 3C 454.3", has been extended in time to follow this new activity phase.
Observations at all wavelengths are encouraged.

Claudia M. Raiteri and Massimo Villata

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WEBT News 43 - July 5, 2007

New campaign on BL Lacertae

Following successful proposals to observe BL Lacertae with XMM-Newton in AO6 and to perform optical spectral monitoring with the 3.5 m Telescopio Nazionale Galileo in AOT15-AOT16, a new radio-to-optical campaign has been organized on this object. The Campaign Manager is Claudia M. Raiteri.

We encourage monitoring at all wavelengths over the whole current observing season, and in particular during the XMM-Newton pointings.

A web page on the campaign is available here .

Claudia M. Raiteri and Massimo Villata

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WEBT News 42 - February 21, 2007

3C 279 campaign

Information and instructions concerning the 3C 279 campaign announced in WEBT News 41 can be found here. The Campaign Manager is Valeri Larionov.

Massimo Villata

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WEBT News 41 - February 12, 2007

AO 0235+16 and 3C 279

Two WEBT campaigns are starting on AO 0235+16 and 3C 279, which have been observed in a bright optical state since December 2006.

Regarding AO 0235+16, information on observing strategy/data reduction can be found at the "old" campaign page . Radio-to-optical data collection covers the period between the last 0235 campaign and the end of the current optical season, i.e. May 2005 - April 2007. The Campaign Manager is Claudia M. Raiteri: data can be sent to raiteri@oato.inaf.it.

As regards 3C 279, the campaign is a "past-data collection", at least covering the period April 2006 - January 2007; more information will be posted soon.

Massimo Villata

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WEBT News 40 - May 18, 2006

New campaign on 3C 454.3

Dear All,

in WEBT News 39 it was mentioned the possibility of starting a new campaign on 3C 454.3 to follow the post-outburst phase.

In October we submitted a successful proposal to observe this source with the XMM-Newton satellite. There will be three pointings and the observing windows that we asked for to favour coordinated observations are:

June 24 - July 3, 2006
December 10-20, 2006
May 23-28, 2007

The exact dates are not available yet, but we will let you know as soon as the new long-term XMM-Newton schedule is ready.

In view of these observations we start a new WEBT campaign. Data will be collected from the end of the previous campaign (September 2005) to June 2007, just after the third XMM-Newton pointing. Observations at all wavelengths are welcome.

The Campaign Manager will be Claudia M. Raiteri, who is the PI of the XMM-Newton proposal. A web page for the campaign is available here.

Please, let us know your intention to participate by sending an e-mail to raiteri@to.astro.it and villata@to.astro.it.

Best regards,

Claudia M. Raiteri and Massimo Villata

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WEBT News 39 - September 20, 2005

3C 454.3 radio outburst?

Dear All,

3C 454.3 has shown significant brigthening at high (> 15 GHz) radio frequencies since late August. This increasing flux might represent the propagation of the optical outburst to the radio bands, with progressive delays going towards longer wavelengths.

A very detailed radio (and mm) monitoring at all frequencies in this phase is very important.

This news is not changing our plans on the publication of the 2004-2005 period, as fixed in WEBT News 38, but could sign the start of a new campaign, mainly (but not only) dedicated to the radio behaviour.

All the best,

Massimo Villata

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WEBT News 38 - September 13, 2005

Brief report on the 3C 454.3 outburst campaign and BL Lac 2004

Dear WEBTers,

in the last weeks I have been analysing and assembling the data on 3C 454.3 you have sent up to now.

The result is a preliminary R-band light curve of 1038 data points (from a total of more than 3000 UBVRI observations). As you may remember, our aim is to cover both the 2004-2005 observing season and the current season up to the "end" of the optical outburst.

You can find two (zipped postscript) plots at

http://www.to.astro.it/blazars/webt/3C454.3_2004-2005.zip
http://www.to.astro.it/blazars/webt/3C454.3_2005.zip

The former shows the R-band light curve from early June 2004 to late August 2005, with a total variability range of 4 mags. The latter is an enlargement of the current season, with almost 700 data points showing a fading of 3 mags from the historical maximum R = 12.0 observed by Tom on May 9, when he alerted the WEBT. >From then on, even this preliminary light curve shows that in the following 102 "nights" (from JD 2453499.0 to 2453601.0, i.e. from May 8.5 to August 18.5 UT) we have "covered" 95 nights, i.e. we have no data for 7 nights only. These 2004-2005 data comes from 10 observatories: Abastumani, Crimean, Foggy Bottom, Kitt Peak (MDM), Kyoto, Lulin, Mt. Maidanak, Roque (KVA), Sabadell, and Torino.

Now, since the source has come back to its "standard" brightness (R ~ 15), if we don't see any new brightening event, I would fix the end of the campaign on September 30, together with the deadline for data submission (obviously the last data can be sent a few days later). Then, in October we can prepare a Letter for A&A, where we'll probably present at least the R-band light curve, maybe colour indices, and a radio light curve. All the other bands/frequencies data will be archived for future use.

On another side, the BL Lac 2004 campaign has suffered some delay, mainly due to the above ToO campaign. Anyway, you can find a preliminary R-band light curve at

http://www.to.astro.it/blazars/webt/BLLac1999-2005.zip

where all the WEBT data (1999, 2000, 2001, and 2004 campaigns) are shown. As for BL Lac 2004 (covering from 2002 to early 2005, but also collecting older data), two very large datasets have still to be reduced and/or analysed, which will provide a better sampling/coverage during the last years.

Thank you for your always fantastic participation,

Massimo Villata

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WEBT News 37 - June 15, 2005

3C 454.3 campaign

Dear All,

I was trying to fix the photometric sequence to be used in the 3C 454.3 Campaign 2005.

The situation is a bit complex since there are five photometric sequences in the literature, and none of them is clearly better or worse than the others, and there is not any of them covering all the optical bands with a large number of stars. Thus, at the end, I opted for one of the cheapest choices (in terms of number of references involved), that you can find in the attachment.

One can notice that Star 1 presents a large disagreement among different authors. The reason should be the presence of the faint very close star which can contaminate its flux measure, especially when the measure was done with a photometer or with large apertures.

In our choice, Raiteri et al. report the faintest measures for Star 1, which seem thus not to be affected by the companion. As a consequence, I suggest to use small apertures, in order not to include it.

Another item is the observing strategy to follow in the remaining part of the campaign. Multi-band observations are encouraged in all the available nights. Long intranight series are not currently possible and, in general, are not strictly requested, even if they will be appreciated and welcome.

Reminding that the recommended data format for the submission of optical and NIR instrumental magnitudes is

JD-2453000  3C 454.3         1            2            3            4            ...
515.61148 11.214 0.002 11.325 0.002 11.403 0.002 12.197 0.003 12.950 0.004 ...

I must notice that, while Stars 1 2 3 4 are enough for UBVRI (even if more stars can be useful), this is not true for JHK, where we should get Stars 1 4 7 8, i.e. those having JHK calibration.

Cheers,

Massimo Villata

3C 454.3
(2251+158)

Equat. coord. (J2000.0): R.A.: 22h 53m 57.7s  Dec.:  +16 08' 54''
z = 0.859

Finding chart (10' x 10') from Raiteri et al. 1998


Optical-near-IR photometry of comparison stars   (blue-bold numbers = calibration adopted)

Star \ Band
U B V R I J H K
1 -
-
15.13 (0.04)
-
15.17 (~0.02)
14.70 (0.02)
14.637 (0.012)
14.58 (0.04)
-
14.62 (~0.02)
13.71 (0.02)
13.587 (0.004)
13.62 (0.03)
13.65 (0.04)
13.65 (~0.02)
13.15 (0.02)
13.035 (0.014)
13.10 (0.03)
13.10 (0.04)
-
-
12.545 (0.006)
12.56 (0.04)
12.58 (0.04)
-
-
11.858 (0.002)
-
-
-
-
11.340 (0.002)
-
-
-
-
11.241 (0.002)
-
-
-
2 -
-
15.89 (0.03)
-
15.94 (~0.02)
14.93 (0.02)
15.015 (0.073)
14.96 (0.01)
-
14.94 (~0.02)
13.80 (0.02)
13.798 (0.004)
13.83 (0.03)
-
13.85 (~0.02)
13.19 (0.02)
13.196 (0.005)
13.23 (0.02)
-
-
-
12.633 (0.005)
12.64 (0.02)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
3 -
-
15.52 (0.07)
-
15.42 (~0.02)
15.19 (0.02)
15.292 (0.025)
15.09 (0.03)
-
15.18 (~0.02)
14.44 (0.02)
14.402 (0.012)
14.42 (0.12)
-
14.43 (~0.02)
14.00 (0.02)
13.951 (0.003)
13.98 (0.06)
-
-
-
13.528 (0.004)
13.52 (0.04)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
4 -
-
-
-
15.94 (~0.02)
15.91 (0.05)
15.833 (0.122)
-
-
15.87 (~0.02)
15.21 (0.02)
15.119 (0.015)
-
15.21 (0.06)
15.16 (~0.02)
14.79 (0.02)
14.700 (0.026)
-
14.73 (0.05)
-
-
14.300 (0.007)
-
14.31 (0.05)
-
-
13.792 (0.008)
-
-
-
-
13.403 (0.012)
-
-
-
-
13.349 (0.030)
-
-
-
5 -
-
-
-
16.71 (~0.08)
16.28 (0.05)
16.375 (0.124)
-
-
16.28 (~0.08)
15.30 (0.02)
15.331 (0.009)
-
-
15.42 (~0.08)
14.83 (0.02)
14.844 (0.013)
-
-
-
-
14.334 (0.025)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
6 -
-
-
-
16.35 (~0.11)
16.06 (0.05)
16.179 (0.052)
-
-
16.06 (~0.11)
15.34 (0.02)
15.216 (0.008)
-
-
15.21 (~0.11)
14.83 (0.03)
14.815 (0.010)
-
-
-
-
14.424 (0.017)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
7
-
-
-
-
18.94 (~0.14)
17.00 (0.03)
16.510 (0.090)
-
-
17.10 (~0.14)
15.74 (0.02)
15.614 (0.024)
-
15.76 (0.09)
15.88 (~0.14)
14.94 (0.02)
14.862 (0.009)
-
14.92 (0.08)
-
-
14.204 (0.007)
-
14.26 (0.08)
-
-
13.378 (0.004)
-
-
-
-
12.752 (0.004)
-
-
-
-
12.607 (0.008)
-
-
-
8
-
-
-
-
17.39 (~0.05)
16.85 (0.06)
16.922 (0.151)
-
-
16.85 (~0.05)
15.94 (0.02)
15.789 (0.032)
-
15.86 (0.09)
15.85 (~0.05)
15.34 (0.02)
15.252 (0.011)
-
15.32 (0.09)
-
-
14.754 (0.020)
-
14.80 (0.06)
-
-
14.204 (0.010)
-
-
-
-
13.737 (0.010)
-
-
-
-
13.650 (0.024)
-
-
-

References
Raiteri et al. 1998, A&AS 130, 495   (adopted in BVR
for Stars 1-8)
Gonz�ez-P�ez et al. 2001, AJ 122, 2055   (adopted in I for Stars 1-8 and in JHK for Stars 1 4 7 8)
Smith & Balonek 1998, PASP 110, 1164
Fiorucci et al. 1998, PASP 110, 105
Angione 1971, AJ 76, 412   (adopted in U for Stars 1-8)

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WEBT News 36 - June 6, 2005

3C 454.3 2005

Following the recent optical outburst of 3C 454.3 (2251+158), a WEBT campaign is starting to monitor the source during the remaining phases of the outburst and to collect and assemble the data already taken during the current and last observing seasons, i.e. since spring 2004.

Besides optical monitoring data, also near-IR, mm, and radio data are very welcome.

The recommended data format for the submission of optical and NIR instrumental magnitudes is the usual one (one file per filter):

JD-2453000  3C 454.3         1            2            3            4            ...
515.61148 11.214 0.002 11.325 0.002 11.403 0.002 12.197 0.003 12.950 0.004 ...

where JD (or equivalent UT) must be geocentric at mid exposure (if different, specify it and provide exposure times). The star numbering follows Raiteri et al. 1998 and a minimum of four stars (1-4 preferred) is requested.

People willing to participate in this campaign are invited to send a message to both villata@to.astro.it and Tbalonek@mail.colgate.edu.

The preliminary data sent up to now must be resubmitted in their definitive form to both the above addresses, along with the new data.

Thank you in advance for your participation.

Massimo Villata

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WEBT News 35 - March 18, 2005

OJ 287 2005

A short-term WEBT campaign on OJ 287 has been endorsed to monitor the source just around the XMM-Newton pointing of April 12, 2005.

Besides intensive optical monitoring, also radio and near-IR data are very welcome.

For more information, the campaign web page is at http://www.astro.utu.fi/OJ287MMVI/XMMcampaign.html.

Thank you in advance for your participation.

Massimo Villata

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WEBT News 34 - September 29, 2004

BL Lac 2004

We are planning an updated study on BL Lacertae, following the recent results published in the last two WEBT papers (Villata et al. 2004, A&A 421, 103; Villata et al. 2004, A&A 424, 497).

The main purposes of this work are:

- Updating the optical and radio light curves up to the end of the current observing season (February 2005);

- Collecting light curves at other radio-mm wavelengths;

- Using this new information to confirm (or not) the previous findings, with particular attention to the correlation between optical flux and radio hardness ratios;

- Investigating the variations of the VLBI jet structure, and possible correlations with light curves and spectral behaviour.

Hence, we are looking for new radio, mm, optical data on BL Lacertae. Both unpublished and published data are welcome, starting from the end of the period covered in the above papers (early 2002 for the optical and late 2003 for the radio) up to February 2005; "older" data not included in the previous papers are accepted as well.

The recommended format for the submission of optical data is the usual one (see e.g. WEBT News 22 and links therein).

People willing to participate in this collection, or planning new observations during the current observing season, are invited to send a message to villata@to.astro.it.

Massimo Villata, Claudia M. Raiteri, Uwe Bach

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WEBT News 33 - June 14, 2004

WEBT data publication policy

The WEBT Constitution (Article 2) states that:

The WEBT will function as a non-profit worldwide scientific organization, and the results obtained will be published and shared with the international scientific community.

Moreover, Article 7 says:

The results of the campaign may be published in a dedicated paper after consultation and agreement with the Executive Officer for publication. The Campaign Manager may lead the paper, provided that the paper is submitted to the journal within one year after the end of the campaign; otherwise any decision on the publication of the results will be committed to the care of the Executive Officer for publication and the President.

The recent discussion had with an A&A Editor, who wanted to force us to publish WEBT data in an electronic table available to the public, leads the WEBT Officer for Publication to state the following WEBT data publication policy.

Referring to Article 7, once the paper on the WEBT campaign is published, the WEBT data will remain reserved for a one year period since the publication date and available to the authors of the paper for their own analysis and investigation. Then the data may become available to a generic user upon request to the WEBT Officer for Publication, or via electronic tabular publication in a web site.

Moreover, the A&A Editor requested a footnote to the title in the form:

\footnote{For questions regarding the availability of the data discussed in this paper, please contact Massimo Villata ({\tt villata@to.astro.it})}

This footnote is suggested in all the future WEBT campaign papers.

Massimo Villata

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WEBT News 32 - June 11, 2004

BL Lac radio-optical paper

The radio-optical paper on the WEBT BL Lac campaigns has been accepted for publication in A&A. The corresponding preprint can be retrieved as a zipped-postscript file (0.8 MB, higher quality) or a pdf file (3.6 MB, lower quality) at

http://www.to.astro.it/blazars/bllac2001b_preprint.zip
http://www.to.astro.it/blazars/bllac2001b_preprint.pdf

Massimo Villata

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WEBT News 31 - March 30, 2004

BL Lac Campaign 2001 papers

The optical paper on the BL Lac Campaign 2001 and its extension has been accepted for publication in A&A. The corresponding preprint can be retrieved as a zipped-postscript file (1.2 MB, higher quality) or a pdf file (7.1 MB, lower quality) at

http://www.to.astro.it/blazars/bllac2001a_preprint.zip
http://www.to.astro.it/blazars/bllac2001a_preprint.pdf

In the meantime, another paper on BL Lac including also radio data and time/cross-correlation analyisis has been submitted to A&A. One can download the submitted paper at

http://www.to.astro.it/blazars/bllac2001b_draft.zip
http://www.to.astro.it/blazars/bllac2001b_draft.pdf

Massimo Villata

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WEBT News 30 - December 23, 2003

WEBT leadership 2004-2006

According to the WEBT Constitution (see also WEBT News 1 ), the mandate of the current WEBT executive body will expire on December 31, 2003.

During the last week a new election has been held and the result has been that the following slate will lead the WEBT in the next three years, up to the end of 2006:

President and Executive Officer for publication:    Massimo Villata
Vice President:                                     John Mattox
Webmaster and Executive Officer for data archiving: Claudia Raiteri
Executive Officer for photometry algorithms:        Gino Tosti

Massimo Villata

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WEBT News 29 - October 8, 2003

WEBT campaign on 0716+714

A new WEBT campaign starts today on the BL Lac object S5 0716+71.

The campaign announcement by the Campaign Manager is appended below.

All observers interested in participating in the campaign are invited to send a message to the Campaign Manager (Stefan Wagner) and the WEBT President (Massimo Villata), providing information on their instrumentation and observing plans.

Massimo Villata

    WEBT campaign in conjunction with an INTEGRAL observation of S5 0716+714.

A WEBT campaign to carry out simultaneous multi-wavelength and gamma-ray (INTEGRAL) observations of S5 0716+714 will be organized in October and November 2003.

A 450 ksec INTEGRAL observation of the BL Lacertae object S5 0716+714, proposed by S. Wagner, Landessternwarte Heidelberg will be performed in the period November 11-17, 2003. A WEBT campaign shall ensure simultaneous multifrequency coverage. Since 0716+714 is currently performing a historic maximum in the mm domain, the WEBT campaign will start immediately, culminating in the simultaneous campaign in November 2003.

S5 0716+714 is well known for its Intra-Day Variability (IDV) in the radio and optical bands, and the high-energy part of its spectral energy distribution is expected to peak in the MeV energy domain.

The goal of the INTEGRAL observation is to test the hypothesis that the limit for catastrophic inverse Compton cooling is violated in IDV sources, as suggested by their high brightness temperatures, giving rise to brief outbursts which should be observed by IBIS, the gamma-ray imager on-board the satellite.

Simultaneous multi-frequency observations during this period are crucial to detect the different signatures of this violation.

The INTEGRAL observations will be carried out during the period: November 11 - November 17, 2003

Simultaneous measurements in other bands are requested during the period: November 06 - November 20, 2003

Optical, mm, and radio monitoring should start as soon as possible to allow us to follow the ongoing flare.

Many optical and radio telescopes all around the world will support the ground-based observations, coordinated by S. Wagner.

Further details on the campaign are available on the WEB page:

http://www.lsw.uni-heidelberg.de/users/swagner/0716-nov2003.html

Luisa Ostorero, Stefan Wagner

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WEBT News 28 - July 1, 2003

Upcoming WEBT campaigns

With WEBT News 26 two new WEBT campaigns on AO 0235+16 and 3C 66A were announced.

The campaign on AO 0235+16 is starting today; the Campaign Manager is Claudia M. Raiteri.

The campaign on 3C 66A will start in September; the Campaign Manager is Markus Böttcher.

All information concerning observing strategy, data reduction, etc. can be found in the AO 0235+16 and 3C 66A web pages.

Please, let us know about your participation and observing plans.

Claudia M. Raiteri, Markus Böttcher, Massimo Villata

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WEBT News 27 - April 7, 2003

Report on the BL Lac Campaign 2001 and its extension

As you may remember, the BL Lac Campaign 2001 was extended in the past to include the WEBT campaign of late June 1999 and to collect also optical and radio data starting from about 1990. Moreover, we have then further extended this collection back to 1968, with both published and unpublished data. All this tremendous job has been called "The BL Lac Campaign 2001 and its extension".

The construction of the optical light curves in all this period is almost finished.
The following steps have been performed on (almost) all R-band observations:
- Obtaining standard magnitudes of BL Lac from instrumental ones.
- Discarding bad and unreliable points.
- Binning the data when needed.
- Check of the final light curves for each telescope.
- Putting together different datasets, night by night.
- Estimating the offsets existing among different datasets from overlapping data, and correcting them, night by night.
- Discarding less precise data in favour of higher-precision simultaneous data.
- Final light curves.
The last four steps have still to be done for the other bands (UBVI).

Radio data (37, 22, 14.5, 8.0, 4.8 GHz) from 1968 to 2003 have been provided by Metsähovi and UMRAO.

In the WEBT web site , more precisely at http://www.to.astro.it/blazars/webt/bl2001_results.html , you can find a table with the total number of optical observations (from 1997 to 2002, also including the WEBT campaigns of early and late June 1999) provided by each telescope, and the number of data points extracted from those observations in UBVRI bands (some data of January 2002 have still to be reduced and are not included in the table). There you can also retrieve plots of optical and radio light curves.

As one can see, large gaps are still present in the optical light curve, especially around the first half of 1999 and of 2001: any available data in those periods would be very useful and extremely welcome.

Next news on the work in progress will be sent to participants only. In view of making up the corresponding mailing list and author list, each group from the observatories contributing radio and optical data (see table) is kindly invited to send me some information. As for BL Lac 2000, the author list will be divided in two parts, the first of which will contain one or two names for each group (intended as representatives), and the second one including all other participants. Please, send me an e-mail address and co-author names for each group, following this example for the Torino group:

e-mail: villata@to.astro.it
first list: M. Villata, C. M. Raiteri
second list: S. Crapanzano, L. Lanteri, L. Ostorero

The affiliations will be taken from the BL Lac 2000 paper; if different, please send them too.

Thank you very much.

Massimo Villata

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WEBT News 26 - March 17, 2003

New WEBT campaigns

Two WEBT campaigns are planned for late 2003 - early 2004. 

The first one will be organized on 3C 66A and coordinated with observations at other wavelengths, in particular with a monitoring campaign by RXTE (Sep 15 - Dec 15, 2003). Main goals of the multifrequency campaign are: i) construction of the first simultaneous broad-band (from radio to TeV energies) spectral energy distribution of the source; ii) detection of flux and spectral variability on week-month time scales; iii) detection of fast (intraday) variability; iv) modelling the source behaviour.

The second one will be a radio-optical campaign on AO 0235+16 starting as soon as possible after solar conjunction (say, from July 2003). This blazar presents a quasi-periodic behaviour on a 5-6 year time scale. The next outburst is expected to peak in Feb-March 2004 (+/- 0.5 yr) and the campaign aims at monitoring this event with particular attention to radio-optical correlation.

I would like to know your observing plans for those periods and have an idea on the available telescopes.

Massimo Villata

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WEBT News 25 - January 21, 2003

WEBT publications

A list of WEBT publications is available at the WEBT web site . For each refereed publication one can also find the corresponding link to the ADS Abstract Service and from there links to the journal article.

Massimo Villata and Claudia M. Raiteri

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WEBT News 24 - August 13, 2002

BL Lac 2000 published

The paper on the BL Lac Campaign 2000 has been published in A&A, Volume 390, Number 2 (p. 407). Alternatively, one can find it at the ADS Database by clicking here .

Massimo Villata

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WEBT News 23 - July 30, 2002

Report on BL Lac 2001

The first phase of the construction of the BL Lac Campaign 2001 optical light curves is almost finished.
The following steps have been performed on almost all observations provided:
- Obtaining standard magnitudes of BL Lac from instrumental ones.
- Discarding bad and unreliable points.
- Binning the data when needed.
- Check of the final light curves for each telescope.
While the remaining steps have still to be done:
- Putting together different datasets, night by night.
- Estimating the offsets existing among different datasets from overlapping data, and correcting them, night by night.
- Discarding less precise data in favour of higher-precision simultaneous data.
- Final light curves. 

In the WEBT web site , more precisely at http://www.to.astro.it/blazars/webt/bl2001_results.html , you can find a table with the total number of observations provided by each telescope, and the number of data points extracted from those observations in UBVRI bands (blank cells mean that the reduction is not finished yet). There you can also retrieve the preliminary light curve in R band, collecting 1220 data points.

Besides the optical light curves in 2001-2002, the paper in preparation will contain also radio and optical light curves starting from about 1990, and, in particular, the WEBT campaign of late June 1999.

Thanks to you all for your excellent collaboration.

Massimo Villata

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WEBT News 22 - May 28, 2002

Report on BL Lac 2000 & 2001

The paper on the WEBT BL Lac Campaign 2000 has been accepted for publication in A&A. The corresponding preprint is available at http://www.to.astro.it/blazars/webt/bl00.ps.gz .

The analysis of the data from the BL Lac Campaign 2001 has started. The corresponding period is January 2001 - February 2002. Whoever has still data to submit for this campaign is asked to contact us (villata@to.astro.it ) as soon as possible. 
The suggested data format for instrumental magnitudes is the same of BL Lac 2000 (for more information see http://www.to.astro.it/blazars/2200.htm ):

JD-2452000    BLLac          B            C            H            K
101.53462 15.518 0.007 14.089 0.004 15.848 0.008 15.828 0.008 17.188 0.020

where JD (or equivalent UT) must be geocentric at mid exposure (if different, specify it and provide exposure times). Alternatively, observers may use the same format they used for BL Lac 2000, since programs dedicated to those formats already exist. Observers who already sent data for the preliminary light curve should send the definitive data (if not done yet), or specify whether those data have to be intended as definitive or not.

Moreover, we are also constructing optical and radio BL Lac light curves starting from, say, 1990, which should be included in the paper on the 2001 campaign, where a cross-correlation analysis will be performed. Whoever has unpublished data or information on data already published and wishes to join in this effort is very welcome. Also the WEBT campaign of June 28-30, 1999 (in conjunction with the ASCA observations) will be included in this paper. The relevant data were already collected by Gino Tosti, but possible further data are still accepted.

Massimo Villata and Claudia M. Raiteri

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WEBT News 21 - April 11, 2002

WYBT photometric sequences

The following photometric sequences are suggested for the calibration of WYBT blazars.
WYBT members should use as many reference stars as possible in these sequences, with the warning that in a few cases unusually large errors are present: these stars may be avoided or properly weighted.
A further job might be to precisely identify which stars should be used inside each sequence.

Massimo Villata, Gino Tosti, Michael Carini

Source

Priority
Photometric sequence
0109+224
2
0219+428
1
0235+164
1
González-Pérez et al. 2001
0716+714
1
0735+178
2
0851+202
1
González-Pérez et al. 2001
0954+658
1
1101+384
1
Villata et al. 1998
1156+295
1
1219+285
1
1226+023
2
González-Pérez et al. 2001
1253-055
1
González-Pérez et al. 2001
1510-089
2
González-Pérez et al. 2001
1611+343
2
1633+382
2
1641+399
2
González-Pérez et al. 2001
1652+398
2
González-Pérez et al. 2001
2200+420
1
González-Pérez et al. 2001
2230+114
2
Raiteri et al. 1998
2251+158
1
Raiteri et al. 1998

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WEBT News 20 - March 26, 2002

Rule for the use of the WYBT archive

The WYBT members will send their R-band data (possibly two data points per night per source) to the WYBT archive. This archive will contain all the available R-band data taken by the WYBT members starting from November 15, 2001, with the exception of dense intranight datasets, which are out of the aim of the WYBT. In other words, observers collecting more than two data points on a certain WYBT blazar in a given night may send two or more data to the WYBT archive, as they prefer.

During WEBT campaigns, the data on the WEBT pointed source will be sent also to the WEBT Campaign Manager.

Each WYBT member will remain the owner of his own data and may use and publish them, provided that the following rules are kept.

1) Unpublished WYBT data on a certain source in a given period may be used or published in two ways: i) by the owner himself, provided that not together with other WYBT data (published or not); ii) by the WYBT members contributing those data all together. In other words, no subset of WYBT data may be used, apart from the i) case. In the i) case, the authorship is a choice of the owner; in the ii) case, the authorship will contain all the WYBT members contributing the considered data.

2) In the above ii) case, i.e. when WYBT datasets are used or published as a whole, their use is decided by a committee (the signers of the present document) after examination of the proposals received and consultation with the data owners. Any WYBT member and even non-WYBT members may make proposals for the use of WYBT datasets, and the committee will appoint the PI of the best proposal to lead the proposed work, in the observance of WYBT rules, in particular that on the authorship.

3) Conference presentations of WYBT datasets come within Rule 2, as a particular case. They may be asked for and approved by the committee either as part of a more general proposal or as limited to the presentation itself. In the latter case, they may be asked for even if other PIs are working on those data, provided that with PIs' permission and with reference to the main works.

4) WYBT proposals may also derive from larger (e.g. multifrequency) collaborations, where WYBT data are used in conjunction with other data. Also in this case WYBT rules must be respected.

5) PI appointments may be revoked by the committee when inactivity delays the publication of the relevant WYBT data.

Massimo Villata, Gino Tosti, Michael Carini

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WEBT News 19 - March 8, 2002

WEBT web site address

The new address of the WEBT web site is http://www.to.astro.it/blazars/webt/

Massimo Villata

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WEBT News 18 - January 30, 2002

The optical-radio WEBT

The WEBT collaboration is now extended to the radio bands: the Metsähovi Radio Observatory and the University of Michigan Radio Astronomy Observatory (UMRAO) are members of the WEBT.

Massimo Villata

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WEBT News 17 - October 30, 2001

The WYBT: call for participation

The Whole Year Blazar Telescope (WYBT; see WEBT News 10) will become operative starting from November 15, 2001.
Participation in the WYBT is open to all optical observers who agree with the WYBT document attached below. People may ask for joining the WYBT by replying to this message and filling the following form (possibly before November 15).


Observatory_Name:................................
Observatory_Long(deg):...........................
Observatory_Lat(deg):............................
Observatory_Alt(m):..............................
Observatory_Address:.............................
Observatory_WebPage:.............................

Telescope_Name:..................................
Telescope_Type:..................................
Telescope_Diameter(m):...........................
Telescope_FocalRatio:............................
Telescope_Operation_Mode (automatic,manual):.....

Instr_CCD_Name:..................................
Instr_CCD_NRow:..................................
Instr_CCD_NCol:..................................
Instr_CCD_PIXXsize(microm):......................
Instr_CCD_PIXYsize(microm):......................

Local WYBT Responsible

Resp_FirstName:..................................
Resp_LastName:...................................
Resp_Address:....................................
Resp_Email:......................................


Massimo Villata, Michael Carini, Gino Tosti
 


The WYBT (Whole Year Blazar Telescope)

The WYBT is a consortium of optical observatories which is born from the WEBT (Whole Earth Blazar Telescope). While the WEBT is involved in short-term observing campaigns of blazars, the WYBT participants must assure a continuous monitoring all along the year.

Purposes of the WYBT

The aim of the WYBT is to improve the sampling of the long-term optical light curves of blazars with respect to the results obtained up to now by single observatories. This can be achieved through the coordination of the optical monitoring performed by observatories located all around the Earth.
The WYBT will provide the optical counterpart to the high-energy observations of the next space missions (in particular the scanning mode satellites such as AGILE and GLAST, which will observe many sources at the same time) and of the ground-based Cherenkov telescopes.
The WYBT will also act as an alarm system for both short-term WEBT intensive monitoring and multiwavelength campaigns of sources found in outburst state.

Expected scientific results

Well sampled optical light curves should allow to:
 - recognize the possible existence of characteristic time scales of variability;
 - perform an analysis of the flare shapes to obtain information on the physical processes at the basis of the blazar emission;
 - discover whether there are correlations between the optical flux variations and the flux variations observed in other bands (from radio to the gamma-rays).

Participation in the WYBT

Participation in the WYBT is open to all observers who can dedicate at least 20% of their telescope allocated time to the R-band monitoring of the blazars included in the WYBT blazar list.

Preliminary WYBT blazar list

         Source      Priority

        0109+224        2
        0219+428        1
        0235+164        1
        0716+714        1
        0735+178        2
        0851+202        1
        0954+658        1
        1101+384        1
        1156+295        1
        1219+285        1
        1226+023        2
        1253-055        1
        1510-089        2
        1611+343        2
        1633+382        2
        1641+399        2
        1652+398        2
        2200+420        1
        2230+114        2
        2251+158        1

Observing strategy and data archive

All sources in the WYBT list should be observed in the R (preferably Cousins) band at least two times each night they are observable. Those with priority 1 have to be preferred only in case not all the observable sources can be pointed in a given night (e.g. for meteo reasons).
The data should be submitted to the archive once a week (on Monday) in the following format:
 

Source UTCDate UTCTime JulianDate filter mag err obs_id
0109+224 20010702 023222 2452092.60571 R 15.462 0.053 1

The source name must be that of the WYBT list (IAU name). Dates and times must be those at mid exposure. Obs_id will be assigned by the archive. The source magnitude must be determined using the photometric sequence specified by the WYBT.

Service work

    Comparison sequences (TBD);
    Historical data base (TBD);
    Publication policy (TBD).

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WEBT News 16 - October 26, 2001

BL Lac 2000 & BL Lac 2001

The analysis of the data from the BL Lac Campaign 2000 is taking more time than expected, due to interesting results needing a deeper investigation. We hope to present a first draft of the paper to the co-authors in a few weeks. In the meantime, observers providing data for that campaign should send a list of the co-authors (and affiliations) from their groups.

The collection of the data from the BL Lac Campaign 2001 has started and the deadline for submission is fixed at the end of the year. However, as already done for BL Lac 2000, we extend the data collection outside the spring-summer core-campaign, that is all available data from the whole spring 2001 - winter 2001/2002 season will be accepted.
The suggested data format is the same of BL Lac 2000 (for more information see http://www.to.astro.it/Groups/Extragal/2200.htm):

JD-2452000BLLacBCHK
101.5346215.518 0.00714.089 0.00415.848 0.00815.828 0.00817.188 0.020

where JD (or equivalent UT) must be geocentric at mid exposure (if different, specify it and provide exposure times).
Alternatively, observers may use the same format they used for BL Lac 2000, since programs dedicated to those formats already exist.
Observers who already sent data for the preliminary light curve should send the definitive data, or specify that those data have to be intended as definitive ones.

Massimo Villata and Claudia Raiteri

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WEBT News 15 - July 24, 2001

BL Lac Campaign 2000: final light curves

The final UBVRI light curves of BL Lac 2000 can be found at http://www.to.astro.it/Groups/Extragal/webt/bllac_results.html (pant! pant!).
Some numerical curiosities:
During the BL Lac Campaign 2000 (24×53), 25 (52) different detectors were used, and 15625 (exactly 56!!) observations were done.

Massimo Villata

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WEBT News 14 - June 15, 2001

Report on the BL Lac Campaign 2000

I am finally towards the end of the analysis of the data of the BL Lac Campaign 2000.
It has been a colossal work.
I don't know if someone of you can imagine what it means to put together more than 15,000 observations coming from 22 different observatories, 24 different telescopes, 25 different detectors, in 30 different file (or frame) formats.
I don't recognize myself: I am reduced to a living skeleton (do you feel sorry for me?).
On my desk there is a 12 cm high pile of plots.
The analysis was performed through the following steps:
- Obtaining standard magnitudes of BL Lac from instrumental ones.
- Discarding bad and unreliable points by means of hundreds of plots.
- Binning the data when needed.
- Check of the final light curves for each observatory.
- Putting together different datasets, night by night.
- Discovering the offsets existing among different datasets from overlapping data, and correcting them, night by night.
- Discarding less precise data in favour of higher-precision overlapping data.
- Final light curves.
In the WEBT web site (WEBT campaigns on the left, then Results near BL Lac 2000) you can find a table with the total number of observations provided by each telescope, and the number of data points extracted from those observations in R and B bands (V and I are still to be completed). In the (colour) plots you may retrieve there, you can find the most significant light curves in R band.

I wish to thank all of you for your formidable effort: these are by far the best light curves ever obtained for any blazar.

Massimo Villata

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WEBT News 13 - June 14, 2001

BL Lac Campaign 2001

Some observatories have started or will start soon observations of BL Lac:
Abastumani, Perugia, Torino, Calar Alto, Roque, San Pedro Martir, Clarke and Coyote.
You can see the recent behaviour of BL Lac at the Balonek's page
http://blazar.colgate.edu/~tbalonek/optical/BLLac.010613c.GIF.
I hope that some other observatories will join in soon, especially because we have large longitude gaps at the moment.
Since I have not received any proposal, I appoint myself as Campaign Manager (again! dear me!).
The main information and observing strategy relevant to the campaign remain the same (mutatis mutandis) as for BL Lac 2000 (http://www.to.astro.it/Groups/Extragal/webt/, click on "WEBT Campaigns" on the left and then on "BL Lac 2000"), in particular, I recommend R-band observations to small telescopes, and B,R sequences (plus 1-2 UBVRI sets per night) to telescopes larger than, say, 60 cm.

In a few days (maybe tomorrow) I'll send the promised report on BL Lac 2000 together with some plots, in order you can see the magnificence of the WEBT monitoring.

Massimo Villata

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WEBT News 12 - June 12, 2001

WEBT web site

The new WEBT web site is located at the address http://www.to.astro.it/Groups/Extragal/webt/.
Any WEBT member can check the data on his/her observatory in the List of Participating Observatories (homepage), and communicate possible changes to the Webmaster C.M. Raiteri. Observatories not included in the list may ask for official membership by contacting the Webmaster.
Any other comment/suggestion on the web pages is welcome.

Claudia M. Raiteri

Massimo Villata

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WEBT News 11 - June 12, 2001

BL Lac in outburst

BL Lac has brightened of half a mag in the last few days and of 1 mag in the past two weeks.
I would like to hear your comments on the possibility of starting a new campaign on this object.
How many WEBT members could immediately start observations?
Is anyone willing to act as Campaign Manager?
Can other multifrequency observations be performed?

By the way, I am finally towards the end of the analysis of the thousands of data of the BL Lac Campaign 2000 and shall send you a report in a short time.

Massimo Villata

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WEBT News 10 - April 23, 2001

The Whole Year Blazar Telescope

As well known, the next generation satellites such as AGILE and GLAST will require an extraordinary effort from the point of view of the blazar optical monitoring. The WEBT, as it is now organized, can respond to the need of multiwavelength campaigns during limited periods of time.

Thus, the need of a network able to monitor blazars continuously during all the year is becoming more and more urgent. Some observers participating in the WEBT are already doing it, in some cases for several years. What is now necessary is the organization of these observatories, and the call for other possible participants in this network, which can be called the Whole Year Blazar Telescope (WYBT).

To this aim I have appointed a committee to examine the situation. The persons involved are Michael Carini and Gino Tosti, as they have been among the promotors of these ideas. Among the tasks of this committee, there will be the study of possible solutions for the financial support to the groups from Abastumani and Uzbekistan, which are two of the potential participants in this project.

Massimo Villata

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WEBT News 9 - March 7, 2001

BL Lac 2000, AGILE, GLAST, and MAGIC

Next week I'll present the WEBT at the workshops on AGILE and GLAST in Milano (Italy).

I'll show some results from the BL Lac Campaign 2000 (postscript plots attached below). These results are still preliminary, in the sense that I'm still working on them, and some people have not sent their data yet (but promised them asap).

Contemporaneously, Leo Takalo will present the same plots and the first results from the Mkn 421 Campaign 2001 at the MAGIC meeting in Austria.

Massimo Villata

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WEBT News 8 - February 19, 2001

WEBT campaign on Markarian 421

As you may have seen, Markarian 421 showed large X-ray and TeV fluxes, with large variability, during January (WEBT News 6, January 24th). Now we are organising a WEBT campaign a-posteriori on the optical and radio monitoring of this object during this time.

The aim is to collect all the available data for a combined light curve. At the moment we aim for observations taken between January 1 and February 10, 2001. Since Markarian 421 is a huge galaxy, the optical data should be reduced using similar parameters. We will adopt the methods used in the BL Lac campaign last summer.

The Campaing Manager will be L. Takalo (takalo@oj287.astro.utu.fi), with S. Wagner (S.Wagner@lsw.uni-heidelberg.de) coordinating the multifrequency aspects. Please contact L. Takalo for any optical data you may be able to provide for a joint analysis. If Mrk 421 stays active, we may extend this campaign furher into February/March and will send out another alert.

Leo Takalo

Massimo Villata

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WEBT News 7 - February 19, 2001

WEBT Constitution

The WEBT Constitution (http://astro.fmarion.edu/webt/constitution.html) has been unanimously approved by the six WEBT voting members who have replied. Thus, the Constitution becomes effective starting from today.

Massimo Villata

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WEBT News 6 - January 24, 2001

Mkn 421 high-energy outburst

Mkn 421 is showing strong X-ray and TeV activity (see message below). Leo Takalo is observing the source at the NOT. Other optical observations are encouraged.
Please, let me know if you are observing and keep me informed on possible optical data (finding chart at
http://www.lsw.uni-heidelberg.de/projects/extragalactic/charts/1101+384.html).
This is not an official WEBT campaign at the moment, but interesting optical data could trigger one.

Massimo Villata
 

Date: Mon, 22 Jan 2001 18:00:34 -0500 (EST)
From: Ron Remillard 
Subject: [vsnet-alert 0] Mkn 421 outburst

H.G. Boerst (University of Kiel), N. Goetting (University of Hamburg),
and R. Remillard,(MIT) report on behalf of the HEGRA Collaboration
and the ASM/RXTE Team: 

Following the detection of enhanced X-ray emission from the BL
Lac 
object Markarian 421 with the RXTE All Sky Monitor on,
observations 
with the Cherenkov telescopes of HEGRA (La Palma, Canary
Islands, Spain) 
show very strong TeV activity. Above a threshold energy of 500
GeV, 
daily integrated fluxes (20 minute averages) reach up to 
1, 4, 2, 1.5, 2.5, and 3 times the TeV flux of the Crab Nebula 
in consecutive nights during January 16-22. The ASM observations 
of Mkn 421 in mCrab at 2-12 keV: 44(2) over UT 2001 January
13-18; 
30(3) Jan 19-20; 54(3) on Jan 21, and 80(6) on Jan 22. 
Today's peak is the brightest X-ray flux seen from a BL Lac object 
during the RXTE Mission (since Jan 1996). Observations at other
wavelengths 
are strongly encouraged.  

For updates on the TeV activity and the HEGRA schedule, see
"http://www-hegra.desy.de/mrk-421/".

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WEBT News 5 - December 19, 2000

0716+714 in autumn 2000

This has not been an official WEBT campaign, nevertheless some WEBT observers took data of 0716+714 during and around the ToO SAX pointing of October 30-31, 2000. These optical data will be collected by Enrico Massaro, who will contact concerned people.

Massimo Villata

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WEBT News 4 - December 19, 2000

Financial support

Two WEBT member groups are in financial difficulties and the continuation of their observing activity strongly depends on the possibility of getting financial support.

The Torino Observatory gave some support to one of these groups during the BL Lac Campaign 2000, but our own funds are largely insufficient to cover the above financial requests.

We would like to know if any other WEBT group is in condition to partially help these people, or to hear whether someone knows any way to do it (e.g. proposals for getting funds, etc.)

Massimo Villata

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WEBT News 3 - December 19, 2000

Previous WEBT campaigns

0235+164 1997

The Campaign Manager Claudia Raiteri collected the relevant data and is preparing a paper on the long-term behaviour of the source, which will include also the WEBT campaign results.

Mkn 421 1998

John Mattox is coordinating the reduction and publication of data from the 1998 Multiwavelength Campaign to Study Markarian 421 during a 7 day ASCA exposure. His progress has been slowed by the assumption of a teaching professorship, but he hopes to complete this project within the year 2001. He has not yet obtained results for all observations, but will no longer delay publication because of this.

0716+714 1999

The relevant paper has been recently accepted for publication in A&A.

BL Lac (with SAX) 1999

The SAX PI G. Tagliaferri is preparing a paper containing both X-ray and optical results. There is also the possibility that the optical observations will be better presented in a dedicated short paper.

BL Lac (with ASCA) 1999

The optical results will be either included in the BL Lac 2000 paper, or presented in a dedicated short paper.

Massimo Villata

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WEBT News 2 - December 19, 2000

BL Lac Campaign 2000

The Campaign Manager (CM) of the WEBT BL Lac Campaign 2000 is collecting data over all the period of the current observing season (spring 2000 - winter 2000/2001).

Many participating observatories have already sent their data and many others have promised them within a reasonable time. No news have been heard from a minority of observatories.

This is the last call for data: the deadline for submission of the summer data (relevant to the "core" campaign of July-August) is the end of the millennium (THIS millennium, not the next one). In case of inability to respect this deadline, the CM would like to hear from the interested people about their intentions and plans for submission. Autumn and winter data may be sent within March 2001.

Massimo Villata

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WEBT News 1 - December 19, 2000

WEBT leadership and Constitution

As many of you know, an election for the WEBT executive body has been held last week.

The voting members of the WEBT currently are:
D. Dultzin, J. Mattox, R. Nesci, C. Raiteri, L. Takalo, G. Tosti, S. Wagner.

The result of the voting has been that the following slate will lead the WEBT in the next three years, from today to December 31, 2003:

President: Massimo Villata
Vice President: John Mattox
Webmaster: Claudia Raiteri
Executive Officer for photometry algorithms: Gino Tosti
Executive Officer for data archiving: Roberto Nesci

According to the WEBT Constitution draft (which can be found at
http://astro.fmarion.edu/webt/constitution.html), the WEBT executive body includes (in addition to the officers specified above) an Executive Officer for publication. This office is vacant and an officer for this position is solicited. In the meanwhile it will be held by the President.

Moreover, the WEBT leadership may be enlarged to include other offices. This item is part of the more general discussion on the Constitution itself, which is opened starting from now.

Any comment or suggestion on the Constitution draft by any member of the present e-mailing list is very welcome.

This discussion will drive to the final formulation of the Constitution, to be approved by a two thirds majority of the voting membership in late January.

The current WEBT membership list is coincident with the present e-mailing list: please, check if your observatory is well represented and suggest possible additions/removals.

Massimo Villata and John Mattox