IP PEG

[Douglas]

Hi all,

This not exactly on image, but the result of 114 x 60 sec images, each 60 sec data point was 10 x 6 sec using the Sharpcap Live Stack feature + dark and flat subtraction. My simple set up consists of a 72mm Apo, Skywatcher GTI, Zwo 120mm and photometric 'V' filter. IP Pegasus is a cataclysmic variable star (binary system).

IP PEG

Screenshot 2022-11-29 at 01-53-55 Static Light Curve.png (103.2 KiB) Viewed 1890 times

[oopfan]

Hi Douglas,

Very good. Almost too good. Are you sure that VSTAR is plotting your data and not the data from the AAVSO database? I am attaching a screenshot of a chart I generated using the AAVSO's Enhanced LCG tool. It looks identical to yours. Five people contributed to that dataset. These guys have serious kits, often having apertures of 8 inches or more. The AAVSO encourages its members to use multiple filters and to transform instrumental magnitudes to standard magnitudes yet your V-mags are identical to theirs. Accurate readings of a 14th magnitude star is not easy with your kit using only 60 seconds integration. I would expect greater error the fainter the star becomes. I suggest double checking VSTAR.

Brian

IP Peg AAVSO.png (126.04 KiB) Viewed 1883 times

[Douglas]

Thank you for your reply.
That lightcurve in the AAVSO database is mine. I've been contributing to the AAVSO for years and have over 100,000 data points in their system, in visual, CV, V B and I. This particular star I have made over 2000 data points. I had been a member of the AAVSO for years, also contributing to the Center for Backyard Astrophysics.
I don't use Vstar, I use MaimDl and my kit is serious if the care is done to use it within it's capabilities. As you can see, my lightcurve is almost too good
I used to use an 8" RC, ST7xe EQ6 etc, After a short illness I decided on a lighter set up and back in the groove.
Incidently, I've had a look over the last couple of years of data on this star, and not one imager has transformed their measurements...

Thanks again

[oopfan]

Hi Douglas,

So I was right! The dataset is from the AAVSO database

My apologies. Nice work. By the way, I did consider that but I don't remember seeing your name in the list of data contributors.

Brian

PS: I enjoy Exoplanets and DSCT variables: those having light curves that I can capture in a 3 hour session. Here is one of my captures that I am most proud of: https://u235-varstar.vercel.app/phase-plot/cze-v627
I have a similar kit to yours: William Optics 71mm f/5.9. Unfortunately it is an achromat. It doesn't do well in Blue, so that is why I used a Wratten #12 filter. I don't do much photometry now what with the demands of putting food on the table.

[Douglas]

Hi Brian,

A very nice lightcurve. Amazing what data can be gleaned with modest equipment.
I managed to image and record an eclipse of the exoplanet system Qatar-1, it's in the AAVSO database.

All my data is uploaded using my AAVSO initials 'BPO'.
I also use a little Mak 127 for sun and planets, I'm looking forward to grabbing some pics of Mars in the next few days and weeks, another learning curve..

Clear skies,
Doug.

[oopfan]

Hi Doug,

I'll definitely check out your Qatar-1. It was on my bucket list but clouds always thwarted my efforts.

Brian

[Douglas]

Hi Brian,

Here's the juliandate for the Qatar-1 lightcurve:

JD2458057.297 - 2458057.548 in V

I was using an RC8 F5.5 and a cooled CCD

Doug.

[oopfan]

Doug,

Beautiful!

Screenshot 2022-11-30 at 3.15.38 AM.png (400.96 KiB) Viewed 1811 times

[oopfan]

Hi Doug,

I've only owned refractors but I've toyed with the idea of purchasing an RC8. Others have said to stick with refractors as they are solid and reliable. I yearn for a larger aperture but prices for a 100mm+ APO are astronomical. What would you suggest?

Thanks,
Brian

[timh]

Really impressive stuff .... especially the planetary occultation?

A completely naive question about the Cepheid variable curves ..

As I understand it they are all yellow giants and all have about the same surface temperature (~6K similar to the sun) https://cseligman.com/text/stars/variables.htm

In that case they should all exhibit the same predictable 'black body' shape spectrum --- so it should be possible to compute the entire spectrum and measure more accurate apparent magnitudes purely from measuring in the IR/ near IR part of the spectrum which is the least affected by intervening dust --so direct BV filter measurements would not be needed nowadays? Is that correct?

Tim