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RebeccaTurner's picture
Purpose of this Forum

Welcome to the General AAVSO Discussion forum.  This is the place for beginners and experienced members alike to discuss items that do not fall into any of the other, more specific forums.

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HNL's picture
Astronecroscopy "The death of stars"

I found a reference to the study of stars and how they expire. It was published in 1985, I wondered why the death of stars didn't have a specific name such as: spectroscopy.  So, I thought that it must be a lost name. Or that no one studied it and it was just lost to time.  Well If  you want to know the name of the book, please just reply to this posting.  Best HNL

jtcoin's picture
HL CMa in outburst - how do I report it?

Hello AAVSO,

I am a brand new member. I joined (re-joined) tonight due to an observation this evening.  Because of an interest I have in a couple of double stars near Sirius, I have imaged HL CMa many times.  In looking over my material I found that it was in outburst in April of 2013.  Just tonight I discover that it is again.  It will be days or weeks before I will produce nice pictures and data.  But I thought I would look to notify others who might be interested. It will be cloudy at my site tomorrow and then I have to work.  Perhaps some members would like to observe this event. Thanks in advance for your guidance! Thad (I go by Thad, I need to look into changing my registered name here).

lmk's picture
Hi Thad, HL Cma, a star I

Hi Thad, HL Cma, a star I follow frequently, outbursts at a fairly regular interval, about twice a month or so. Regarding reporting, you need to login with your AAVSO observer code (did you get one before?) For example, mine is "LMK". Then just go to WebObs to enter your observations, a nice user friendly web form.

I observe it only visually, and being so close to Sirius, requires a high magnification to get the glare of that star out of the field. If you will try to do CCD estimates, it may also require some careful reductions to avoid the glare from Sirius to affect the photometry as well.

Good luck with it!


PYG's picture
Re: HL CMa

If you want to report an outburst of HL CMa (or any other CV) so that the rest of the VS community can monitor it, then you need to join an alert list - CVnet, BAAVSS alert  or VSnet.  You can then announce your outburst (checking first that your outburst is new through the aavso DB.  There isn't much point in announcing an ongoing outburst) with time/date & magnitude.  The active subscribers to these lists have e-mail delivery, so observers will know at once what's going on in the CV world.  Forums are not the place to announce new outbursts or any other interesting VS activity, but rather to discuss VS matters in general.  You will of course also need to report it to the AAVSO as Mike mentions in the above message. Some observers will be notified of stars in outburst through the 'My News Flash' system, but each observer defines their own settings as to what and when they receive these messages, so your not guaranteed in reaching the whole community.

Here are the URL's for the three mentioned lists...




Good luck and welcome to the AAVSO!


jtcoin's picture
Mike and Gary thanks so much!

Mike and Gary thanks so much!! You have really helped me to get started.  I did find the HL CMa data compiled by AAVSO and generated a light curve.  I see, Mike, that as many times I have imaged the region it must just be bad luck that I only caught an outburst twice! Thanks so much for the links, Gary!

As I have been engaged in astrometric reductions to measure my double stars (looking for possible orbital and proper motions) I have worked hard to reduce the diffusion from Sirius. I found a background subtraction routine in Image J (an image analysis program developed by the NIH (therefore free!) with an Astronomy pluggin by Prof. Hessen in Germany). It seems to work very well to remove Sririus' contibution from the background.

Thanks again so much for the hearty welcomes and guidance!


lmk's picture
You're welcome Thad! BTW, I

You're welcome Thad! BTW, I wonder how well these automated background removal routines really work? It seems it depends heavily on the specifics of each telescope. For example, my Newtonian has strong secondary diffraction spikes, which I must rotate the tube so one doesn't cover HL! Even SCT's and refractors may have other irregular internal reflections and such, which would result in a complex, non-uniform background effect, and is magnified enormously by such an extreme interference so nearby.


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