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.

46 223 By Bikeman 2 weeks ago

BL Lac in action

American Association of Variable Star Observers (AAVSO)
bskiff Mon, 10/17/2022 - 15:53

     As can be seen in recent AAVSO data, the classic blazar BL Lac has become active again.  As recently as Sep 25 it was down at V ~14.2, but is now bouncing around V ~12.5.  Two recent ATels report activity in the visible and at gamma-rays:



This activity is not unusual, but a potential precursor to an outburst.

1st galactic SN fire-drill: open for registration

American Association of Variable Star Observers (AAVSO)
Bikeman Wed, 09/14/2022 - 23:13

SNEWS (SuperNova Early Warning System) is exactly what its name implies: it is a system that can give us an early warning about a certain type of supernova happening in our own galaxy (and neighborhood) when a massive star ends its life and collapses into a neutron star or even a black hole. When it happens, neutrino detectors will detect the signature of the collapse even before we can see the event in optical spectrum because the collapse will take some time to propagate to the layers of the star that are transparent to optical wavelengths.

RFO GX 339-4

tjmaccarone Mon, 09/05/2022 - 19:41

Hi, folks,

GX 339-4 is in outburst.  We will be observing it with JWST on September 10 from 00:42:23 to 3:03:17 UT.  It's currently about 16.5 mag in V, and it's likely to be getting brighter.

The goal of the JWST program is to look at the rapid variability, so sub-second timescale time series photometry would be especially valuable for anyone who has that capability, but any time series photometry with accurate timestamping would be useful.

Time Domain Astrophysics link on HEN webpage

American Association of Variable Star Observers (AAVSO)
daveh Mon, 06/27/2022 - 17:51

The HEN webpage now includes a section for members interested in time domain astrophysics. This includes Gamma Ray Bursts/GRB afterglows, galactic supernova, and gravitational wave detection. All of these time domain phenomena will require optical followup by AAVSO members and other observers. Members of the HEN are currently involved in projects in all of these three research areas, as discussed in the link. Time domain astrophysics is a new and exciting research area in high energy phenomena.

Sco X-1 acting up?

American Association of Variable Star Observers (AAVSO)
Bikeman Sat, 05/28/2022 - 05:55

There have been two Neil-Gehrels-SWIFT triggers coming from the direction of SCO X-1 in the past 2 days.



Does anyone know what's up there? Should we observe Sco X-1 in the optical more often? This would be most interesting for observers in Australia I guess.

FITS images from a video stream

American Association of Variable Star Observers (AAVSO)
SGEO Mon, 05/16/2022 - 18:58

If I am trying to capture photometry for a SuperNova event, one of my fears would be over exposing the images. That would be sad: to be on target for the event but then capturing nothing of value.

What if the DSLR was put into a video mode? Is there experience with video-to-fits? That way you could stack your fits images to any SNR you would like.



How to prepare for DSLR observations of the coming SN event

American Association of Variable Star Observers (AAVSO)
SGEO Thu, 05/05/2022 - 14:43

In the presentations about SNEWS they talk about how amateurs can contribute with DSLR observations.

The advantages are:
-  It would be quick to setup
-  It's 3 color photometry automatically

But there are problems:
- the target might be very bright
- what if comp stars are not available?

I'd like to start a discussion about how to be prepared to do DSLR observations of a SN.

If the event is so bright that it can be done in daylight, how does one calibrate and establish comps?