[vsnet-alert 2561] (fwd) WEBT update #16 - 3C 279 bright

[Taichi Kato <tkato>]

   Circulated by permission of the WEBT team:

Subject: WEBT update #16 - 3C 279 bright

Dear WEBT Collaborators,

The Torino group has discovered that 3C 279 is now bright - see
http://vsnet.to.astro.it/Groups/Extragal/3c279.htm

The COMPTON Observatory was already pointing at 3C 279 (for a COMPTEL
OBSERVATION). EGRET was turned-on on January 20th. 

Bob Hartman reports:
The quicklook analysis of the first 33 hours on 3C 279 shows that
it is bright, similar to the average level EGRET observed in June 91
and during the 2 weeks prior to the big flare in Feb 96.
        
The CGRO observation will continue through at least Feb. 2, 1999.

Today, Ian McHardy began daily RXTE observations, and if further increase
is observed, may invoke his approved 300ksec RXTE TOO for full-out coverage
(continuous except for Earth occultation). If Ian invokes full-out coverage
RXTE monitoring, I suggest that the WEBT should strive for as much of
24 hours/day coverage as possible during the ~1/2 week of dense RXTE
observation. I wanted to alert you now to this prospect. I will send e-mail
if this comes about with more details. I attach Ian's e-mail which 
stresses the value of low energy (e.g. optical) coverage to fully 
utilize the X-ray and gamma-ray observations to "investigate emission 
mechanism and where the seed photons come from."

Observations at a density of ~1/day are of interest in the mean time.
I've established a web page for this flare at
http://gamma.bu.edu/webt//3c279_1999.html

John

p.s. 

The On-Line Discussion of the Optical Monitoring of Blazars 
During the GLAST Mission is in full progress - see:
http://gamma.bu.edu/webt/glast-era/

It has become clear that before deciding how many new telescopes are needed for
an automatic telescope network (ATN), it is crucial to consider the growing 
number of automatic telescopes which are being commissioned or planned, and 
their potential contribution to blazar monitoring during the GLAST mission. 
The effort which will be made with "human operated" telescopes must also be 
considered. 

I've established a preliminary list of observatories for which an 
intention has been expressed to monitor blazars during the GLAST mission at  
http://gamma.bu.edu/webt/glast-era/commitments.html
Please let me know if you would like to be added to this list.

Also, I'm beginning to think about how NASA might further the Optical 
Monitoring of Blazars During the GLAST Mission by supplying equipment
to existing observatories. I would like to converse with each of you
about this if you are interested.

John

----- Forwarded message from Ian McHardy <imh@astro.soton.ac.uk> -----
Date: Mon, 25 Jan 1999 11:51:44 +0000 (BST)
From: Ian McHardy <imh@astro.soton.ac.uk>
Subject: Re: 3C 279 bright

We've started our TOO, but not flat out. Dick Miller confirms other
observations of a high optical level, but a bit lower (few tenths of a
mag) than a few days ago. As a compromise, we're now looking once a day. A
full-out TOO would be more or less continous. As far as we can see
(crudely) at present, the X-rays agree with the gamma-rays and optical, ie
it's high, but not through the roof or rapidly flaring. However if you
decide to uprate the Egret TOO, then I guess we would ask to uprate the
RXTE TOO to something like twice a day. If it then starts to rise rapidly
then we could further uprate, but it doesn't look as if the data warrants
a flat-out campaign at present. But we all need to keep a very close eye
on what is happening. 

Also, we should bear in mind the moon. We're just over a week past new
moon, so timing is not good. It really is critical that we get coverage in
the low energy (opt/ir/mm-submm) bands. If we just get another
Gamma-ray/X-ray flare it won't tell us anything too much about the
emission mechanism and where the seed photons come from. 

Ian

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