BL Lac bright (again)

Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 08/11/2020 - 19:52

This prototype of the blazars apparently reached a very bright state in the past week (Rc = 12.33, thus V ~13.0), per the ATel by Tatiana Grishina and Valeri Larionov using a 70cm telescope at Crimea:

http://www.astronomerstelegram.org/?read=13930

This seems to be confirmed by ASAS-SN data as well.  It looks as though the AAVSO comp stars are a bit soft, and could be improved using data from 2013PASP..125..344P as well as the Peter Stetson files at CADC (B and V for fainter stars). 

\Brian

Affiliation
American Association of Variable Star Observers (AAVSO)
Fermi light curve

BL Lac is one of the objects that is under a constant watch by the Fermi/LAT gamma ray telescope, the continuously updated light curve can be inspected here:

https://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lig…

As you can see, at the time of writing this, the flux is increasing again. Just like S5 1803+78, which had its own campaign here recently, the flare doesn't seem to have a single peak and BL Lac seems to have more "action" coming in the next days (weeks?).

Cheers

HB

 

Affiliation
American Association of Variable Star Observers (AAVSO)
BL Lac observations

I have been observing this blazar with a remote telescope since September 2. The light curve of AAVSO shows peaks, during which the maximum magnitude was up to 12.6 V. I think it would be good if the observation campaign was announced for BL Lac during such active state. At the night 19/20 September (UTC), I measured its magnitude at 12.271 R +/-0.002.
Best regards,
Filipp.

Affiliation
American Association of Variable Star Observers (AAVSO)
Another bright state of BL Lac

I report my latest magnitude measurements of BL Lac with remote telescope (0.61-m f/6.5 corrected Dall-Kirkham) of Burke-Gaffney Observatory in Halifax, Nova Scotia, Canada. Images were obtained on October 6, 2020 with Astrodon V filter (photometric Johnson V) and with Astrodon R filter (photometric Cousins R) for 300 and 180 seconds. The following magnitudes were measured from comparison to nearby stars from the AAVSO star chart X25633GT: V = 12.633 +/- 0.002 (JD 2459128.655463) and R = 12.081 +/- 0.002 (JD 2459128.662616). Images are available here: http://www.ap.smu.ca/~bgo/sm/images/BLLAC-ID12305-OC145635-GR5173-V.fit and http://www.ap.smu.ca/~bgo/sm/images/BLLAC-ID12306-OC145636-GR5174-R.fit This is the brightest magnitude of the blazar from the start date of my observations on September 2, 2020.