Am a beginner Astro person finding my way. I took some "sky" pics , no known nebulas etc just sky in vicinity of milky way and am trying to process using Siril both 1.06 ans 1.20. All seems ok till I get to the Photometry area and the "Image Plate Solver" where it asks for R Ascension and Declination, what figures do I put into these spaces?. Also up the top on the left is an area where you put in the specifications of the "star" or nebula you shot so Siril can do a comparison. What happewns as in my case where I didnt shoot anything in particular and just shot an area of sky ? Can Siril operate withoiut this information ? I am using a Skywatcher Sky adventurer 2i. Help and advice needed please.
Siril Photometry, Image plate Solver
I don't see why you should get into Photometry at all if all you need is a stacked up image of sorts. It is unclear what you want to do and with what, to be honest, so hard to advise. The standard procedure for pre-processing astro photos is given in the link below. Are you following it?
Siril - Manual pre-processing
Siril - Manual pre-processing
Hi Andrea, I am processing my shots in Siril including calibration frames and then I want to see what I have photographed in the sky, I think it is what is known as stretching is it not? This is then why I proceed into the rest of Siril to process .
i think the op is talking about the photometric colour calibration area in siril which works by either putting the objects name so that the RA/DEC numbers can be obtained automatically or manually putting the ra/dec(astronomical object sky co-ordinates) in by hand.
If you used a goto mount and performed plate solving etc this info gets written into the fits file header and you can then get that metadata from the image .
In your case.
as your just pointing at a random region of sky then perhaps upload oneof your subs your to astrometry.net.
It should be able to platesolve your image and give you the ra/dec coordinates.
If you used a goto mount and performed plate solving etc this info gets written into the fits file header and you can then get that metadata from the image .
In your case.
as your just pointing at a random region of sky then perhaps upload oneof your subs your to astrometry.net.
It should be able to platesolve your image and give you the ra/dec coordinates.
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I'm afraid it is not. Stretching is the operation(s) needed to generate a non-linear image from the stacked up linear sum of the series of images you captured, all of which represent the captured scene in linear fashion. If you want to know what portion of the sky you captured (thus knowing the image center RA and Dec coordinates) then save your image (whether linear or non-linear it doesn't matter) in fits format and head here:
https://nova.astrometry.net/upload
Upload your image and wait for the site to do its job and it will give all the info you need to plug in into Siril at a later time, if needs be. It will also tell what objects you captured and given a link to a planetarium web site so you can see it in context.
https://nova.astrometry.net/upload
Upload your image and wait for the site to do its job and it will give all the info you need to plug in into Siril at a later time, if needs be. It will also tell what objects you captured and given a link to a planetarium web site so you can see it in context.
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Thanks all for comment. What info goes into the box R Ascension and Declination? Does not seem enough space foir the true figures.?
Russell HodderThanks all for comment. What info goes into the box R Ascension and Declination? Does not seem enough space foir the true figures.?
https://www.celestron.com/blogs/knowledgebase/what-are-ra-and-dec
To get comfortable with these numbers download copy of stellarium and you can see how differnt objects have their astronomical locations displayed using this co-ordinate system.It also helps you learn the niht sky and help your pointing be "not so random"
I put a photo into the Astrometry site but got a failed result. How does or can it compute this pic not knowing where it was taken , latitude and declination ?
Russell Hodder:
I put a photo into the Astrometry site but got a failed result. How does or can it compute this pic not knowing where it was taken , latitude and declination ?
It has a sky model database that it searches .It uses pattern recognition id imagine.
Conveted an image to jpg and was successful. Gave R asc as 185.688 and dec as -60deg 24'. is this the info I enter ? how do I fit it into the space given on Siril ? What do I call it in Siril ?
I haven't used Siril much yet. But seeing as it has Photometric Color Calibration, I'm going to give it a try again.
For now though, it might be easiest if you can skip or opt out of the Photometric Color Calibration step, just for now so you can continue ahead to get your initial stretch and see what kind of data you're working with.
A "stretch" adjusts the color values in the image, typically raising the values along the lower end of the mid-tones section of the histogram so that you can see faint details that are otherwise hidden there among the shadows, while values for shadows and highlights typically remain the same to avoid clipping the data at the ends of the histogram.
What the Photometric Color Calibration does is it'll attempt to balance the color in the image based on stars found in the image, and their known star colors. A very cool feature.
Would you mind sharing a link to your Astrometry.net results page? I'm curious to see what image you provided, and if it can be stretched and uploaded again to get a better result.
Thanks!
Nikko
For now though, it might be easiest if you can skip or opt out of the Photometric Color Calibration step, just for now so you can continue ahead to get your initial stretch and see what kind of data you're working with.
A "stretch" adjusts the color values in the image, typically raising the values along the lower end of the mid-tones section of the histogram so that you can see faint details that are otherwise hidden there among the shadows, while values for shadows and highlights typically remain the same to avoid clipping the data at the ends of the histogram.
What the Photometric Color Calibration does is it'll attempt to balance the color in the image based on stars found in the image, and their known star colors. A very cool feature.
Would you mind sharing a link to your Astrometry.net results page? I'm curious to see what image you provided, and if it can be stretched and uploaded again to get a better result.
Thanks!
Nikko
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Russell Hodder:
Conveted an image to jpg and was successful. Gave R asc as 185.688 and dec as -60deg 24'. is this the info I enter ? how do I fit it into the space given on Siril ? What do I call it in Siril ?
So what you have there is your Right Ascension (RA) and Declination (Dec) coordinate values, but RA is shown in decimal format while Dec is in degrees-minutes-seconds format, where single quote mark comes after minutes, and double quote mark comes after seconds.
The Astrometry results page should list both formats for both RA and Dec. For RA though, it'll list hours-minutes-seconds instead of degrees-minutes-seconds, since the Earth's rotation can be measured in hours.
The minutes and seconds are arc-minutes and arc-seconds. Both hours and degrees can be divided into arc-minutes, and arc-minutes divided into arc-seconds. The "arc" portion of each term indicates measuring along a curve or a circle.
Check the results page again and look for the coordinate values for RA in hours-min-sec, and Dec in deg-min-sec. You can enter those into Siril in the respective fields provided.
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https://nova.astrometry.net/user_images/7996605#annotated image sent to Astrometry.
In the section on photometric colour calibration that I refer to are boxes with RA AND DEC LISTED , FIRST TWO BOXES are - +, - + then decimal values alongside each. What do I put into the first two boxes ? Am I only concerned with the boxes with the decimal values in ?
as per your result from astrometry:Center (RA, hms):12h 22m 45.109s
1st box on left 12
middle box 22
last box 45.109
Do the same for your declination Center (Dec, dms):-60° 24' 00.807"
1st box on left 12
middle box 22
last box 45.109
Do the same for your declination Center (Dec, dms):-60° 24' 00.807"