“Ethics” of using historic data

[tomato]

Last night I couldn’t image my planned new target because of a persistent cloud bank so I went for a galaxy that I had imaged last year and got around 6 hrs of data, not enough to do it justice. However, I have around 7 hrs of subs from this time last year so planned to combine them, but somehow I feel this might be cheating a little?
Technically I don’t think there is a problem, any detail visible on the galaxy won’t have changed, and modern software will easily deal with changes in the background, but if this is a common practice why don’t I see lots of images of 20+ hours from imagers who have been doing this for while?

[andrew s]

Hardly a difficult ethical issue. Just do it. Regards Andrew 

[michael.h.f.wilkinson]

I combine data from several sessions regularly (how else could I collect 12h+ on the Heart and Soul). Often these sessions are just a few days apart, but I don't see what difference the time delay makes. I have even combined my data with that of others (with permission and due acknowledgment). Happens all the time

[pete_l]

1 hour ago, tomato said:

why don’t I see lots of images of 20+ hours

Probably because people collect sufficient data for a nice looking end result and then move on to a different target. It is, after all, a hobby. Nobody is being judged or assessed on the forensic detail of what they produce.

[iantaylor2uk]

No it's not cheating

[Richard_]

It's not cheating unless you do this for one of the SGL competitions (the rules say you have to capture the data during the time frame of the competition). I'm sure the reasoning is to level the playing field for newbies against long timers  who may already have lots of historical data at their disposal. 

I don't see any issues if you're doing it just for fun. Perhaps a lot of people don't do it due to different pixel scales and focal length of telescopes used over time or perhaps their computer simply struggles with stacking so much data. If you've used the same equipment for your subs then why not use as much data as your computer can handle? 

[scotty38]

I seem to think I do see fairly regular posts of folk using data from xyz dates in the past. As above, apart from competitions, it's not like the targets have changed much in our lifetimes so data from last year/last week/yesterday makes no difference as far as I can tell....

[ollypenrice]

2 hours ago, tomato said:

 but if this is a common practice why don’t I see lots of images of 20+ hours from imagers who have been doing this for while?

Because you haven't been looking at mine? 🤣

I do it absolutely all the time. To cheat you have to break the rules. Where are these rules? Natural justice and common decency certainly state that we shouldn't steal other people's data and that, if we use it with permission, we give a credit. In the write up it seems helpful to others to state the 'when and where' of the capture so I usually list that (if I can remember, but sometimes I forget to include it in my files.)

I think it would be crazy not to use all the good data I have on a target. My rule is to make the best image I can.

Olly

[Sp@ce_d]

Most of my images take me months if not over a year to collect enough data. The last one I posted a few weeks back (M101) I started in April last year & I only managed 10 & a half hours of usable data! You'd have to be very lucky with the weather alone (at least in the UK) to get enough on just one night. There are some targets I've been chipping away at that are only reachable for a short time before I loose astro darkness so if the weather & Moon don't play nice a whole year can be lost.  I keep all my data.. seems crazy not to with the amount of effort gone into it. For pretty much 6 months of the year the obsy gets mothballed as I don't have enough usable astro darkness anyway... but during that time I do wear a hair shirt to make up for it 😆. 

[tomato]

Thanks for the replies, which are along the lines of what I expected. I suppose I have been at this game long enough now to start to move into the realms of combining historic data, and by that I mean data 2, 3 or more years old, rather than that captured during the current season, which as folks have pointed out, is standard practice.

I'm still surprised that that long integration images are not more common place on this forum, given how long digital imaging has been around and how easy it is to combine data of different pedigrees these days.