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
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
The renewed flaring in gamma ray was also seen by MAGIC, see this ATEL
http://www.astronomerstelegram.org/?read=14032
CS
HB
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.
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.