58 replies to this topic

[Xilman]

I've just used the plots that come with the camera specs (like those in the link you posted) to translate camera gain to e-/ADU  but I suspect it will vary between cameras (and suppliers) and  I don't know if  there is a similar graph specifically for the Seestar

 

Cheers

Robin

Thanks Robin.

 

I just consulted those graphs again, now that you have told me what to look for. With a full well depth of 11200 e- and a 12-bit ADC, the e-/ADU must be 2.73 to reach the full well capacity. Squinting at those graphs suggests this is reached at a gain of zero.

 

However, the read noise approximately halves at gain=80. At gain=0 the RN is 2.5 e- and at gain=100 it is 1.0 e-.

 

As you hint, the best approach will be suck it and see. An element of that is already in operation as an image of a Landolt field has been taken with a view to measuring colour transformation coefficients. A set has been published by AAVSO but it will be a useful exercise to see if the performance my S50 matches theirs.

 

ATM I don't take darks and flats before, during and after a set of observations. I should do so.

[rgrokett]

There is also the "HOYS - Hunting Outbursting Young Stars, is a citizen science project run by Dr Dirk Froebrich (University of Kent)" et. al. that supports data collected from Seestar users.  "photometric monitoring of young stellar clusters to find outbursting" similar to the AVVSO work. 

 

https://hoys.space/

 

 

Russell

[robin_astro]

 With a full well depth of 11200 e- and a 12-bit ADC, the e-/ADU must be 2.73 to reach the full well capacity. Squinting at those graphs suggests this is reached at a gain of zero.

 

However, the read noise approximately halves at gain=80. At gain=0 the RN is 2.5 e- and at gain=100 it is 1.0 e-.

 

 

If you are running anywhere near to full well the 2.5e- read noise is neither here nor there really as it is still much less than the photon noise.  The lower read noise at higher gain can help where you are not working near the full well depth though (eg with faint targets or when summing many short exposures) 

 

Cheers

Robin

[Xilman]

If you are running anywhere near to full well the 2.5e- read noise is neither here nor there really as it is still much less than the photon noise.  The lower read noise at higher gain can help where you are not working near the full well depth though (eg with faint targets or when summing many short exposures) 

 

Cheers

Robin

Thanks Robin.

 

"summing many short exposures" is an excellent summary of the typical use of a SS50 AFAICT.  I will stop worrying about read noise..

[mikef0924]

I built a small array of three S50s that are equatorially mounted for AP and photometry projects. I use Seestar_ALP for control and automation. My photometry runs utilize 60s subs, dithering off, and gains set at 100. Green channel, Below is a recent result observing BH Aur.  Tycho Tracker was used for the measurements and analysis.

 

 

The computed period is in close agreement with the published value. 

 

 

[pairofdocs]

My senior synthesis in college was to compute the orbits of three eclipsing binaries: Algol, RZ Cas and OO Aql. With data I personally collected. I had thought when (if I ever) retire I would restart the project. Now that I have a SeeStar it will make.the project easier.

[Xilman]

My senior synthesis in college was to compute the orbits of three eclipsing binaries: Algol, RZ Cas and OO Aql. With data I personally collected. I had thought when (if I ever) retire I would restart the project. Now that I have a SeeStar it will make.the project easier.

Go for it!
 

[Airship]

These images of the T CrB field were taken this morning using a Seestar S30 (left) and S50 (right) showing the considerably wider field of the S30. Note the glare of epsilon CrB in the upper left corner of the S30 field. This illustrates how the S30 may serve as an aid for star-hopping by providing real-time finder charts. Reduction of the green channel gave nearly the same value for T CrB; Tri-G 10.00 from the S30 and 10.02 for the S50.

 

 

Neat stuff!

 

[Airship]

The little camera that could... I peeked outside this morning and saw moon shadows on my backyard indicating that it might be clear. Just in case it was clear enough to get a quick image of T CrB I put on my slippers, grabbed my Seestar S30 and headed outside. Sure enough, it had cleared enough to give it a try. If I can get at least 4 decent source images that's enough to get a reasonable brightness estimate. I ended up my my standard 10 minute set. Woohoo! Normally, I'd leave it out running a plan to use the hours before dawn, but the poor little thing was cold enough, so I shut it down, wrapped it in a towel, and brought it back inside before heading back to bed.

 

 

And yep, no eruption yet...