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All Year Object

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#1 mic1970

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Posted 16 July 2019 - 01:04 PM

Is there a good newbie DSO that is available all year?  I've been looking at these photos where the photographer took weeks to months to collect.  I work early hours, so it is hard to stay out long on week nights in the warmer half of the year. 



#2 J A VOLK

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Posted 16 July 2019 - 01:14 PM

M81/M82 and the Cat's Eye Nebula are always above the horizon, of course the higher the better so check a star map or planetarium program for their elevation at various times and dates.
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#3 mic1970

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Posted 16 July 2019 - 01:39 PM

Thanks I will.  Now the question: can I get good weather on the correct nights. 

 

 

M81/M82 and the Cat's Eye Nebula are always above the horizon, of course the higher the better so check a star map or planetarium program for their elevation at various times and dates.



#4 2ghouls

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Posted 16 July 2019 - 01:46 PM

A lot will depend on your latitude and local horizons. Generally, the answer is: objects closer to the pole. Check out this site if you don't already use it: https://telescopius.com/

 

A few that spring to mind that I think might be good for at least a large portion of the year, and are good newbie targets: M81/82 (maybe all year), Double Cluster (maybe all year) M31 (Summer - early winter), M45 (Fall-Spring)


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#5 mic1970

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Posted 16 July 2019 - 01:53 PM

I am outside St. Louis.  I have a very clean view from the north star to southern skies.  In the west, I can see almost anything if it over 30 degrees or so off the ground.  SW is my worst view due to safety lights in a grave yard. 

 

Thanks.

 

A lot will depend on your latitude and local horizons. Generally, the answer is: objects closer to the pole. Check out this site if you don't already use it: https://telescopius.com/

 

A few that spring to mind that I think might be good for at least a large portion of the year, and are good newbie targets: M81/82 (maybe all year), Double Cluster (maybe all year) M31 (Summer - early winter), M45 (Fall-Spring)



#6 mic1970

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Posted 16 July 2019 - 01:55 PM

I guess need to ask this question once I get started.  When I have a good night, due I stack those files with each other...and...then stack that single with other singles.  Or, do you add a nights pics to the pile and restack all the individual files each time.  Does that make sense?



#7 WadeH237

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Posted 16 July 2019 - 02:16 PM

At your latitude in St. Louis, the celestial pole is less than 40 degrees above the horizon.  For something to be available all year, it needs to be "circumpolar".  In other words, it needs to be close enough to the pole that it never sets.

 

You really don't want to image something that's directly on the horizon, so an "all year" object needs to be even closer to the celestial pole.  If, your example, you don't want to image below 25 degrees above the horizon, then your "all year" objects would need to be within 15 degrees of the north celestial pole.

 

Off the top of my head, I can't think of any imaging showpiece objects with a declination greater than 75 degrees north.  You would be better off having a list of a few summer objects and a few winter objects.  Late spring and early fall would also work for most summer objects, and late fall and early spring would also work for most of the winter objects.


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#8 mic1970

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Posted 16 July 2019 - 02:23 PM

That is what I thinking. 

 

PS... how do you like your Edge HD?  It is on my bucket list.

 

 

At your latitude in St. Louis, the celestial pole is less than 40 degrees above the horizon.  For something to be available all year, it needs to be "circumpolar".  In other words, it needs to be close enough to the pole that it never sets.

 

You really don't want to image something that's directly on the horizon, so an "all year" object needs to be even closer to the celestial pole.  If, your example, you don't want to image below 25 degrees above the horizon, then your "all year" objects would need to be within 15 degrees of the north celestial pole.

 

Off the top of my head, I can't think of any imaging showpiece objects with a declination greater than 75 degrees north.  You would be better off having a list of a few summer objects and a few winter objects.  Late spring and early fall would also work for most summer objects, and late fall and early spring would also work for most of the winter objects.



#9 OldManSky

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Posted 16 July 2019 - 02:25 PM

I am outside St. Louis.  I have a very clean view from the north star to southern skies.  In the west, I can see almost anything if it over 30 degrees or so off the ground.  SW is my worst view due to safety lights in a grave yard. 

Just wondering why the residents of a graveyard need lights to see at night...?


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#10 mic1970

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Posted 16 July 2019 - 02:27 PM

LOL...  Good point.  They serve two purposes, keep the kids out at night (as it is right off a state highway.  They also light up some angels. 

 

 

Just wondering why the residents of a graveyard need lights to see at night...?



#11 t_image

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Posted 16 July 2019 - 02:43 PM

Just wondering why the residents of a graveyard need lights to see at night...?

frown.gif .

A large open cemetery used to be a good place for immediately dark surroundings for my astro work....

Until Pokeman Go became a thing and graveyards were locations of interest in the game.

One time there was an almost caravan of cars coming in and out of the location on weekend nights until the owners started locking the place down at night.

What a shame.



#12 mic1970

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Posted 16 July 2019 - 02:52 PM

Well when I was young and dumb, it was a place to meet and share an adult beverage we weren't supposed to have.  We were smart enough to leave things well enough alone.  Others are not. 



#13 2ghouls

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Posted 16 July 2019 - 02:58 PM

I guess need to ask this question once I get started.  When I have a good night, due I stack those files with each other...and...then stack that single with other singles.  Or, do you add a nights pics to the pile and restack all the individual files each time.  Does that make sense?

I do the latter. Stack all the individual subs together from many nights of imaging. It definitely helps to use platesolving so that you are imaging the same section of sky each night. My tolerance is 15 pixels.



#14 DaveB

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Posted 16 July 2019 - 03:02 PM

If you are patient, you should consider revisiting a given target year after year until you get enough integration time to satisfy you. It gives you several benefits:

  • You can process it this year and get feedback on possible areas of improvement.
  • You can process it next year (or the year after that...) with two (or more) years' worth of subs and a year more of processing experience. It is fun to compare against your previous attempt.

Just remember to keep all of your raw frames and your master calibration frames (flats, darks, bias) together. I use a folder structure to assist me in doing this. From the parent folder on down, my folder tree looks like this:

 

target -> equipment -> year -> type

 

So, an example of a folder path might look like this:

  • M5/10RCwithFR/2019/raw (this holds all of my raw frames taken with my RC and a focal reducer)
  • M5/10RCwithFR/2019/cal (this holds my master calibration frames)
  • M5/SV80/2019/raw (this holds raw frames taken with my refractor)

There are certainly other ways of organizing things, and I periodically change how I organize my files, but this is my latest/best model that works for me.

 

EDIT: Note that I image from an observatory in my backyard, so my imaging train stays constant over many nights. If this was a nightly setup/teardown, then my date field would be more granular than just a year - it would probably be a yyyymmdd year code.


Edited by DaveB, 16 July 2019 - 03:04 PM.

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#15 mic1970

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Posted 16 July 2019 - 03:15 PM

Do you ever image with that 20" Starmaster?

 

If you are patient, you should consider revisiting a given target year after year until you get enough integration time to satisfy you. It gives you several benefits:

  • You can process it this year and get feedback on possible areas of improvement.
  • You can process it next year (or the year after that...) with two (or more) years' worth of subs and a year more of processing experience. It is fun to compare against your previous attempt.

Just remember to keep all of your raw frames and your master calibration frames (flats, darks, bias) together. I use a folder structure to assist me in doing this. From the parent folder on down, my folder tree looks like this:

 

target -> equipment -> year -> type

 

So, an example of a folder path might look like this:

  • M5/10RCwithFR/2019/raw (this holds all of my raw frames taken with my RC and a focal reducer)
  • M5/10RCwithFR/2019/cal (this holds my master calibration frames)
  • M5/SV80/2019/raw (this holds raw frames taken with my refractor)

There are certainly other ways of organizing things, and I periodically change how I organize my files, but this is my latest/best model that works for me.

 

EDIT: Note that I image from an observatory in my backyard, so my imaging train stays constant over many nights. If this was a nightly setup/teardown, then my date field would be more granular than just a year - it would probably be a yyyymmdd year code.



#16 WadeH237

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Posted 16 July 2019 - 03:31 PM

PS... how do you like your Edge HD?  It is on my bucket list.

I like it quite a lot.

 

If you are looking for a longish focal length scope in that size range, it's probably the best bang-for-the-buck that you could find.



#17 DaveB

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Posted 16 July 2019 - 03:46 PM

Do you ever image with that 20" Starmaster?

Not yet, although I have considered doing some lunar imaging with it.



#18 mic1970

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Posted 16 July 2019 - 03:54 PM

Not yet, although I have considered doing some lunar imaging with it.

Try some planets with it.  It would be awesome. 



#19 TelescopeGreg

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Posted 17 July 2019 - 12:51 AM

I guess need to ask this question once I get started.  When I have a good night, due I stack those files with each other...and...then stack that single with other singles.  Or, do you add a nights pics to the pile and restack all the individual files each time.  Does that make sense?

I would say it depends on the software you are using.  For Deep Sky Stacker, you would put each night's data (lights, darks, flats, dark-flats) in their own tab.  If you have calibration files that apply to the entire data set, put those in the Main tab.  Then hit the big button and let it crunch away.  I always let it realign everything, just to be sure.



#20 WadeH237

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Posted 17 July 2019 - 06:30 AM

I guess need to ask this question once I get started.  When I have a good night, due I stack those files with each other...and...then stack that single with other singles.  Or, do you add a nights pics to the pile and restack all the individual files each time.  Does that make sense?

You should stack all the individual subs at once.  The more samples the stacking and rejection algorithms have to work with, the better the result.

 

Sometimes I'll stack just a single night's worth of data just to evaluate it.  But when I go to make the final image, I always re-stack them as a single set with the individual subs from all nights.



#21 the Elf

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Posted 17 July 2019 - 02:20 PM

The stacking process benefits a lot from similar subs and too a certain extend needs subs that are not too different. The critical point is coverage by thin clouds. If you have some obstructed by clouds sort them out. All subs must have the same ISO/gain and exposure time. It does not matter if the time between two subs was 5 minutes or 5 years. You can put all images from several nights in one pot, provided same ISO and exposure. If you tried different settings or some with a filter and some without you need to stack them group wise. All can be stacked with the same flats, provided you did not take off the camera or rotate it. If you want to go imaging the next night, keep camera and scope connected and don't touch it. When it comes to very dim object the temperature of darks plays a role, for bright beginner targets this is probably not your biggest problem.

It is commen practice to post a "pls process my <whatever>" and post a link to dropbox or google drive. The normal way is posting the stack. In case you are totally lost in the individual frames you can post it all. I'm not scared of downloading 3GB and taking a look. As soon as you have the stacking fixed you would post the stack only. From the unprocessed data we can draw more conclusions about the data quality than from your final result. The pro way of stacking is to do an automatic analysis of all subs by software (e.g. PixInsight has a script called subframe selector). It happens now and then that one night was poor and you would drop a full nights set as too many blurry subs ruin the sharp ones. I don't know if there are free tools to do that. DSS has a best of percentage setting, but I don't know what is uses as the sort out criterion.

If your set is 20+ subs all stackers should do a great job. I'd say 7 is the absolute minimum for defect pixel correction. On the other hand 50 won't do much better than 20. The point is not how many subs but how much over all exposure time you have. 30 x 2min is better than 10 x 2min of course, but there is no point in doing 60 x 1min instead as far as noise is concerned. If your mount has poor tracking it makes perfect sense as the stars are less elongated.

Hm, too much input, I guess.


Edited by the Elf, 17 July 2019 - 02:24 PM.


#22 mic1970

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Posted 17 July 2019 - 03:10 PM

Thank you.  Are these take away's (for me) correct for shots across multiple nights:

 

1.  Use the same camera and telescope

2.  Center of the same point - near by star or something in the target

3.  Always use the same ISO and exposure times

4.  (From another post) Put all this information in the file name

5.  Until I get better - Stick to brighter object and 1 minute exposures (I have no guiding skills yet)

6.  If I have a night of poor seeing or poor focus, leave them out

     a.  Let software figure that out.  Need to figure out how with my software (Deep Sky Stacker or PIMP)

 

I can't leave my equipment together.  What do I do about darks and flats? 

 

 

 

The stacking process benefits a lot from similar subs and too a certain extend needs subs that are not too different. The critical point is coverage by thin clouds. If you have some obstructed by clouds sort them out. All subs must have the same ISO/gain and exposure time. It does not matter if the time between two subs was 5 minutes or 5 years. You can put all images from several nights in one pot, provided same ISO and exposure. If you tried different settings or some with a filter and some without you need to stack them group wise. All can be stacked with the same flats, provided you did not take off the camera or rotate it. If you want to go imaging the next night, keep camera and scope connected and don't touch it. When it comes to very dim object the temperature of darks plays a role, for bright beginner targets this is probably not your biggest problem.

It is commen practice to post a "pls process my <whatever>" and post a link to dropbox or google drive. The normal way is posting the stack. In case you are totally lost in the individual frames you can post it all. I'm not scared of downloading 3GB and taking a look. As soon as you have the stacking fixed you would post the stack only. From the unprocessed data we can draw more conclusions about the data quality than from your final result. The pro way of stacking is to do an automatic analysis of all subs by software (e.g. PixInsight has a script called subframe selector). It happens now and then that one night was poor and you would drop a full nights set as too many blurry subs ruin the sharp ones. I don't know if there are free tools to do that. DSS has a best of percentage setting, but I don't know what is uses as the sort out criterion.

If your set is 20+ subs all stackers should do a great job. I'd say 7 is the absolute minimum for defect pixel correction. On the other hand 50 won't do much better than 20. The point is not how many subs but how much over all exposure time you have. 30 x 2min is better than 10 x 2min of course, but there is no point in doing 60 x 1min instead as far as noise is concerned. If your mount has poor tracking it makes perfect sense as the stars are less elongated.

Hm, too much input, I guess.


Edited by mic1970, 17 July 2019 - 03:20 PM.


#23 the Elf

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Posted 18 July 2019 - 03:55 PM

Darks are taken at the same ISO with the same exposure time and at the same temperature in general. If you use PixInsight and have bias frames as well the exposure time can be longer or shorter as PI scales the dark. The temperature can be the same. No need to wast the time at night, darks can be taken at daytime. If you have a cooled astro camera dial in the same temperature. If uncooled try to find a temperature info. For my T3i I can read the tag "CameraTemperature" using exiftool to match the darks. (see my video "preparing your first imaging session..."). You take flats every night because the dust motes move all the time. You want to calibrate the dark dots and doughnuts out. DSS supports groups of images (i.e. nights) with individual flats. Take bias frames as well. For a DSLR bias and flat darks are practically equal. I never used flat darks. (Flat darks are darks with the exposure time of the flats, used to calibrate the flats. This makes sense when the flats exposure is several seconds).



#24 Im2bent

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Posted 18 July 2019 - 05:41 PM

Where might one find this video? Just search YouTube for the elf?

#25 the Elf

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Posted 19 July 2019 - 01:12 AM

There is a link in my signature to my Channel and a link to my homepage. The underlinde parts are the links. Go to media on my homepage to find more usefull links beside my own tutorials.


Edited by the Elf, 19 July 2019 - 01:13 AM.



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