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REQ vetting of my first measurements

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astrolopitec's picture
REQ vetting of my first measurements


I've uploaded through Vphot a 3 hours series at 1 minute interval (182 shots) of TT ari through V filter and fully calibrated (even if Vphot shows red).

While the result numbers look quite plausible. I worry of contributing bad data. So I'd appreciate any comments and guidance from experienced people. 

My data runs from 2456208.67920 to 2456208.81977 under observer code HJUC.

Any one interested to see the images or the sequence TTarisec1 in Vphot let me know your observer code and I will  give you share access .

I've already given share access to  KTC, roe, and HQA


Juan Herrero

KTC's picture
Looks like a good start

Hi Juan!

Your data look like a good start.

Some comments:

- If you add the FITS keyword CALSTAT = BDF  then VPHOT will not show a red flag for calibration

- Can your scope/CCD software provide airmass?  None is currently provided in the FITS header.

-FWHM of stars in most of your images is less than 2.0.  I recommend defocusing a bit so that you get FWHM 2.2 to reduce the risk of photometry errors due to undersampling.

I'm still on the road, so this is a quick review of your images.  All for now.

astrolopitec's picture
Hi Yes my combination of


Yes my combination of Sitech telescope control and CCDsoft does provide air mass.  But I calibrated the data using Nebulosity and poof! Many of the keywords disappeared from the header. So I recalibrated again all the data using CCDsoft only and that fixed the problem. I also discovered that CCDsoft has a handy bulk header editor so it was easy to insert the CALSTAT parm in all the frames.

I will defocus to 2.2 FWHM on my next run. Hopefully tomorrow night.


KTC's picture
Some software is not designed to do science, but astrophotograpy

I calibrated the data using Nebulosity and poof! Many of the keywords disappeared from the header.

Do you mean this software?

Based on a quick glance at that page, and the other kinds of image manipulation software it does not seem to be designed for scientific imaging.  (And you mention that it strips away some FITS keywords.)

I recommend you use software that was designed with science/photometry/astrometry/spectroscopy in mind.

Yes, the CCDSoft bulk FITS header editor comes in handy if you only want to add/change one or two keywords.  But you can use scripts to do more complex FITS header editing tasks.

Good luck!

PS.  I have three Si-Tech servo rigs, and hope to add another soon.  Recently I added a Renishaw incremental read head and 20 micron tape to the RA axis of one scope with a poor performing worm drive.  I get angular resolution of about 0.1 arcsecond per encoder tick.  I won't say that I tured a sow's ear into a silk purse, but I'm impressed with the improvement in RA drive performance.

astrolopitec's picture
Yes that is the software.

Yes that is the software. Very good for DSLR pretty pictures.

I also have a Renishaw at 0.16 arcsec per tick. Finally tracking the way it was meant to be!

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