# Question on Data Sheet for targets

**URL:** https://forum.telescopius.com/t/question-on-data-sheet-for-targets/541
**Category:** General Questions
**Tags:** targets, tips, telescope-simulator
**Created:** [June 29, 2022, 8:49pm UTC](https://forum.telescopius.com/t/question-on-data-sheet-for-targets/541 "2022-06-29T20:49:22Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![scubafish](https://forum.telescopius.com/letter_avatar_proxy/v4/letter/s/7bcc69/32.png) [@scubafish](https://forum.telescopius.com/u/scubafish)
#### Post date: [June 29, 2022, 8:49pm UTC](https://forum.telescopius.com/t/question-on-data-sheet-for-targets/541/1 "2022-06-29T20:49:22Z")

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Newbie here. I am trying to make sense of the target Datasheet - specifically the sub-class of the target. Is there a legend for what the letters and numbers mean?

For example - NGC7380 has a data sheet showing a sub class of III3pn. What does this mean?

As a newbie I am trying to work out what images with RGB and what needs more specialised filters - HA, OIII etc. I was hoping the sub-class may give me a hint. Didn’t want to spend time imaging something that needs a set of filters I don’t own…

Thanks for any advice.

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### Author: ![sebagr](https://forum.telescopius.com/user_avatar/forum.telescopius.com/sebagr/32/6_2.png) [@sebagr](https://forum.telescopius.com/u/sebagr)
#### Post date: [April 28, 2023, 8:05pm UTC](https://forum.telescopius.com/t/question-on-data-sheet-for-targets/541/2 "2023-04-28T20:05:32Z")

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Many sub-classes do have that kind of information, but I’m afraid I can’t explain all those references very well.

Most of that information came from databases which had those explanations somewhere else (like appendixes).

At any rate, I’m planning a big target database update soon which will hopefully shed some light into this kind of doubts. As well as a feature to let users tag objects as good targets for certain filters, and share their experience 🙂

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### Author: ![Wayne\_Frey](https://forum.telescopius.com/user_avatar/forum.telescopius.com/wayne_frey/32/108_2.png) [@Wayne\_Frey](https://forum.telescopius.com/u/Wayne_Frey)
#### Post date: [May 31, 2023, 6:40pm UTC](https://forum.telescopius.com/t/question-on-data-sheet-for-targets/541/3 "2023-05-31T18:40:17Z")

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That is a Trumpler classification for open star clusters. There is a different one for galaxies, planetary nebulae, and globular clusters. Each from a different astronomer. Galaxies from Hubble, later revised by De Vaucouleurs. Planetary Nebulae VV (Vorontsov-Velyaminov). Globular Clusters by Shapley & Sawyer Hogg.