by Ann » Mon Sep 04, 2023 5:01 pm
alter-ego wrote: ↑Mon Sep 04, 2023 2:08 am
Ann wrote: ↑Sun Sep 03, 2023 4:50 am
alter-ego wrote: ↑Sun Sep 03, 2023 12:16 am
Based on GAIA pm data for this star, I calculate the time difference to be ~23 years.
• There is a large proper motion in declination. Proper motion in RA and Dec = 5.6 mas/yr and 101 mas/yr respectively, or a total pm ≈ 102 mas/yr
• The angular change ≈ 2.3 arcseconds
→ 2.3 arcseconds ÷ 0.1 arcseconds/yr = 23 years
Thanks, alter-ego, I'm so impressed by your skills in math! Thanks for using it here at Starship Asterisk* to help us understand things that have to do with APODs!
You have apparently identified the "flying star". I used Simbad to try to identify it, to get a designation for it, but I failed.
All I got was the star next to it (to the west of it), 2MASS J21010772+6808005.
Did you get a designation for the fast moving star? How else could you get a proper motion for it?
In order to know the star's proper motion we need to know its true distance, right? Oh, you just calculated its displacement across the sky between the two images, right?
No, wait, you used Gaia! How did you do that? I have never used Gaia to try to find a star!
Ann
Thank you, I'm glad I could help.
If you can independently find the coordinates for a star in question, you can enter them in a search box at the Gaia website:
Gaia Home page, then click search tab. Depending on how well you know the coordinates you can also enter a search area size to include the star. However, it's probably better to go to the Aladin website via the
CDS website. Search for the Iris nebula. Here you'll get a familiar scalable image of the nebula. You can select the Gaia DR3 layer (may take a while to load). Click on the star in question (Gaia layer shows hollow squares) and the data shows up on the screen:
Aladin Lite.jpg
Turns out this star only has numbering ID:
Gaia DR3 2270239585757069312.
Alternatively, I like using the free downloadable Aladin desktop which is easier to get more results with less work:
Aladin Desktop.jpg
Enabling the DR3 layer, and clicking on the star, you'll see a scrollable row of Gaia data at the bottom. Clicking on the
Source_ID box takes you a Vizier page which includes other star cross-IDs:
Vizier Cross-IDs.jpg
Hope this helps you.
Thank you so much for your help! Maybe I'll be able to use Gaia myself in the future, but I
am slow on the uptake, really. I remember how much bystander had to sweat in order to make me understand how to post large images as attachments without uploading them to my computer. Remember that, bystander?
But thanks again, alter-ego! I very much appreciate your help! Maybe I'll even be able to use Gaia myself thanks to you, but I make no promises.
Ann
[quote=alter-ego post_id=333521 time=1693793302 user_id=125299]
[quote=Ann post_id=333473 time=1693716619 user_id=129702]
[quote=alter-ego post_id=333469 time=1693700197 user_id=125299]
Based on GAIA pm data for this star, I calculate the time difference to be ~23 years.
• There is a large proper motion in declination. Proper motion in RA and Dec = 5.6 mas/yr and 101 mas/yr respectively, or a total pm ≈ 102 mas/yr
• The angular change ≈ 2.3 arcseconds
→ 2.3 arcseconds ÷ 0.1 arcseconds/yr = 23 years
[/quote]
Thanks, alter-ego, I'm so impressed by your skills in math! Thanks for using it here at Starship Asterisk* to help us understand things that have to do with APODs!
You have apparently identified the "flying star". I used Simbad to try to identify it, to get a designation for it, but I failed. [url=http://simbad.cds.unistra.fr/simbad/sim-coo?Coord=21+01+07.7453228113%2B68+08+00.458484349&CooFrame=ICRS&CooEqui=2000.0&CooEpoch=J2000&Radius.unit=arcmin&submit=Query+around&Radius=2]All I got[/url] was the star next to it (to the west of it), 2MASS J21010772+6808005.
Did you get a designation for the fast moving star? How else could you get a proper motion for it?
In order to know the star's proper motion we need to know its true distance, right? Oh, you just calculated its displacement across the sky between the two images, right?
[b][color=#0040FF]No, wait, you used Gaia! How did you do that? I have never used Gaia to try to find a star![/color][/b]
Ann
[/quote]
Thank you, I'm glad I could help.
If you can independently find the coordinates for a star in question, you can enter them in a search box at the Gaia website: [url=https://gea.esac.esa.int/archive/]Gaia Home page[/url], then click search tab. Depending on how well you know the coordinates you can also enter a search area size to include the star. However, it's probably better to go to the Aladin website via the [url=https://cds.unistra.fr/] CDS[/url] website. Search for the Iris nebula. Here you'll get a familiar scalable image of the nebula. You can select the Gaia DR3 layer (may take a while to load). Click on the star in question (Gaia layer shows hollow squares) and the data shows up on the screen:
Aladin Lite.jpg
Turns out this star only has numbering ID: [color=#0000FF]Gaia DR3 2270239585757069312[/color].
Alternatively, I like using the free downloadable Aladin desktop which is easier to get more results with less work:
Aladin Desktop.jpg
Enabling the DR3 layer, and clicking on the star, you'll see a scrollable row of Gaia data at the bottom. Clicking on the [i]Source_ID[/i] box takes you a Vizier page which includes other star cross-IDs:
Vizier Cross-IDs.jpg
Hope this helps you.
[/quote]
Thank you so much for your help! Maybe I'll be able to use Gaia myself in the future, but I [i]am[/i] slow on the uptake, really. I remember how much bystander had to sweat in order to make me understand how to post large images as attachments without uploading them to my computer. Remember that, bystander?
But thanks again, alter-ego! I very much appreciate your help! Maybe I'll even be able to use Gaia myself thanks to you, but I make no promises.
Ann