[Aavso-photometry] Image archiving...

[Shawn Dvorak]

I, too, keep the original and calibrated images, as well as the 
calibration frames (flats & darks), on CD-Rs.  I occasionally compress 
the images using hcompress if I have a lot of data for a given night - 
it's a hassle splitting a night's data across two CDs.  I'm up to 220 
CDs of data, including lots of old data from a CB245 that I rarely refer 
to (but wouldn't dream of discarding).  I actually make two copies, with 
one going offsite to work and one staying at home.

Lately, though, I've been thinking about using a mirrored pair of large 
ATA or SATA drives, and only make a single CD copy that will go 
offsite.  Mirroring the drives will ensure that a disk failure won't 
require tedious reloading of data, and even a 250 GB drive will provide 
enough space to accommodate all my existing data as well as another few 
years' worth.  I use Linux for my main workstation, and will probably 
put squashfs file systems on disk, which will provide compressed, 
read-only storage.

Shawn

Bob Koff wrote:

> Bill,
>
> I've been archiving all of my images, and keeping them indefinitely.  
> I am saving both raw and calibrated images, writing them to CD/DVD.  I 
> try to remember to include the calibration frames on the CD's as well 
> as the images.
>
> Putting them on a CD or DVD means they don't take up much room to 
> physically store, and the media is pretty cheap.  So it's practical to 
> save everything, just in case it's needed later.
>
> This was learned the hard way...
>
> Regards,
>
> Bob Koff
> Antelope Hills Observatory
>
> Bill Goff wrote:
>
>> I'm wondering what the habits are of folks on this list for archiving 
>> image frames.
>>
>> 1.  How long do you save your images, just till you've reported 
>> results, a year or more or forever?  It seems that as time goes on 
>> those older images would have less value.  I guess if I had images 
>> from a 5m+ scope that I waited a year for time on, I might feel 
>> differently, but I don't have that problem.  I've got some images 
>> from a cookbook camera that are several years old, can't image 
>> needing them...
>>
>> 2.  Do you save the raw images or just the calibrated ones?  I've 
>> found a couple of occasions where the calibration was incorrect and 
>> having the raw images saved the day.  I've also found that if I just 
>> wanted to perform a new reduction  such as including a new star, 
>> having to chase down old calibrate frames and recalibrate was a pain, 
>> having saved calibrated images was easier.
>>
>> For now, I've started saving the calibrated images in addition to the 
>> raw.  That gives me a way to recalibrate if necessary and after some 
>> time (yet to be determined) dump the raw ones.  At one point the GTN 
>> people talked about image archiving on their machines, so I'd hate to 
>> dump something that someone else might have a use for someday, but 
>> I've not heard anything on this recently.
>>
>> On the other hand, writing it all to CD or DVD's might be a solution, 
>> if they're important enough to keep.  Any one care to comment?
>>
>> Bill
>>
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