High Energy Network (HEN)

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Information on the observation and analysis of stars and other objects that are sources of x-rays and gamma rays.

18 114 By tjmaccarone 1 week 5 days ago

Rapid optical variability of S4 0954+65

American Association of Variable Star Observers (AAVSO)
Bikeman Sat, 03/13/2021 - 14:27

I'd like to draw attention to


which reports "Rapid optical variability of S4 0954+65" .

This object is already well observed by observers here at this moment, but in the light of this ATEL , if you have the time to do it, some higher cadence observations (more than one data point per night) may be useful for future research.

Clear Skies


BL Lac still exciting, other notable ATLEs

American Association of Variable Star Observers (AAVSO)
Bikeman Mon, 01/25/2021 - 16:03

A series of recent ATELs indicates that the pros are very excited about BL Lac lately:

http://www.astronomerstelegram.org/?read=14328 "The flaring blazar BL Lacertae observed below R=11.5, a new record for its optical brightness"

http://www.astronomerstelegram.org/?read=14329 "Erratum to ATel #14328"

http://www.astronomerstelegram.org/?read=14330 "Fermi-LAT gamma-ray flare in BL Lacertae contemporaneous with optical flaring activity"

http://www.astronomerstelegram.org/?read=14334 "Multicolor-optical observation of the flaring blazar BL Lacertae"

Free Zoom Colloquium on X-ray Binaries

American Association of Variable Star Observers (AAVSO)
gsivakoff Tue, 09/22/2020 - 15:36


Hi All,

Given the clear connection between CVs and X-ray binaries, I wanted to make this announcement.

Interested in some of my team's recent results? Join my Zoom presentation of a Colloquium for the University of Alberta Physics Department this Friday. Please note that this talk was designed with undergraduate Physics students in mind!!

Title: Winds of Change around Black Holes

Presenter: Gregory Sivakoff (University of Alberta)

Time: Friday, September 25 3:00 PM Mountain Time (US and Canada)

Observations of Blazar S5 1803+78 critically needed

American Association of Variable Star Observers (AAVSO)
daveh Tue, 04/14/2020 - 19:33

Blazar S5 1803+78 is rapidly brightnening. Observers in Spain and Germany have contributed recent observations, but the weather in Europe has been overcast and probably will be until at least this weekend. Observations outside of these areas are encouraged until the weather clears. The next several days may be critical as the blazar seems to be reaching a peak magnitude. Please make observations if possible and upload to light curve for S5 1803+78.


Dave (HDHA)