<p>You can query TIC by Gaia ID. Using the <a href="https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html" rel="nofollow noreferrer">MAST Portal</a>, MAST Catalogs, TESS Input v7, Advanced Search form, I specified:</p>

<p><code>GAIA ID: 4052922352453886976</code></p>

<p>and got a single result:</p>

<pre><code>TIC ID (ID):            50559830
RA (ra):                275.945292 (18:23:46.870)
Dec (dec):              -25.672353 (-25:40:20.47)
TESS Mag. (Tmag):       13.579
Version (version):      20180610
UCAC ID (UCAC):         322-168973
2MASS ID (TWOMASS):     18234686-2540204
GAIA ID (GAIA):         4052922352453886976
GAIA G Mag. (GAIAmag):  14.5068
</code></pre>

<p>Since the MAST portal currently provides TICv7, the Gaia ID is probably from Gaia DR1.
The <a href="https://outerspace.stsci.edu/display/TESS/TIC+and+CTL+Data+Release+Notes+Home+Page" rel="nofollow noreferrer">TIC release notes</a> say Gaia DR2 data are new in TICv8.</p>

<blockquote>
  <p>9&nbsp;&nbsp;GAIA&nbsp;&nbsp;The matched Gaia DR2 identifier has been updated in TICv8.
  Gaia IDs in TICv8 are included for stars that are found in the Gaia-provided Gaia-2MASS look-up table.
  These identifiers have been updated by the Gaia team from DR1 to DR2, and may not be consistent between TICv7 and TICv8.</p>
</blockquote>

CC BY-SA 4.0
2019-05-19T17:38:19.340Z
From the [Gaia table description](https://gea.esac.esa.int/archive/documentation/GDR2/Gaia_archive/chap_datamodel/sec_dm_main_tables/ssec_dm_gaia_source.html) the `source_id` encodes "...the provenance (data processing centre where it was created)...". Does this mean that each TIC target could correspond to multiple `source_id`s? That is, can multiple Gaia observations be of the same target? With this, the TIC table may only link a single `source_id` and so some `source_id`s may correspond to targets in the TIC table, but may not show up there?
Shiania White
CC BY-SA 4.0
2019-05-19T19:05:24.993Z
If the [TIC paper](https://arxiv.org/abs/1706.00495) and some test queries don't answer that question, try the TESS help desk?
Mike G
CC BY-SA 4.0
2019-05-19T22:36:33.587Z
Thank you for the reference. For others reading this, from the [TIC Paper](https://arxiv.org/abs/1706.00495), "Gaia IDs in TIC-6 are included for stars which are found in the Gaia-provided Gaia-2MASS look-up table. For TIC stars with more than one associated Gaia magnitude, the ID of the brightest matching Gaia source is provided." So it would seem that multiple Gaia `source_id`s will correspond to a single TIC ID, but only the brightest will be shown. So if the `source_id` is not the brightest one, the above method will not work, and RA/DEC will still be needed (unless I'm missing something).
Shiania White
CC BY-SA 4.0
2019-05-18T17:19:17.270Z
2019-05-18T17:19:17.270Z
Mike G
<p>The TESS input catalog (TIC) "uses the GAIA DR2 catalog as a base" according to the <a href="https://tess.mit.edu/science/tess-input-catalogue/" rel="noreferrer">catalog's website</a>. The Gaia DR2 database provides <code>source_id</code>s for each observation of a target. I want to get the TIC number for a target based on the Gaia <code>source_id</code>. Is there an accepted way of doing this that I'm missing?</p>

<p>To be more specific, I can get a list of Cepheids from Gaia DR2 using <a href="https://gea.esac.esa.int/archive/" rel="noreferrer">their archive</a> and the ADQL command <code>select * from gaiadr2.vari_cepheid</code>. The first result has the Gaia <code>source_id</code> as <code>4052922352453886976</code>. How can I find the TIC number for this target star? Is the best way of doing this using the RA and DEC of the Gaia observation and finding the closest match in the TIC? Since the TIC is based on the Gaia DR2, I would assume there would be a direct corresponding target and finding the closest RA and DEC match would be unnecessary.</p>

<gaia><tess>
Obtaining TESS input catalog (TIC) IDs for Gaia `source_ids`?
Shiania White
# Obtaining TESS input catalog (TIC) IDs for Gaia `source_ids`?

(Asked by: username_0 on 2019-05-17)

The TESS input catalog (TIC) "uses the GAIA DR2 catalog as a base" according to the [catalog's website](https://tess.mit.edu/science/tess-input-catalogue/). The Gaia DR2 database provides `source_id`s for each observation of a target. I want to get the TIC number for a target based on the Gaia `source_id`. Is there an accepted way of doing this that I'm missing?

To be more specific, I can get a list of Cepheids from Gaia DR2 using [their archive](https://gea.esac.esa.int/archive/) and the ADQL command `select * from gaiadr2.vari_cepheid`. The first result has the Gaia `source_id` as `4052922352453886976`. How can I find the TIC number for this target star? Is the best way of doing this using the RA and DEC of the Gaia observation and finding the closest match in the TIC? Since the TIC is based on the Gaia DR2, I would assume there would be a direct corresponding target and finding the closest RA and DEC match would be unnecessary.

**Tags:** gaia, tess

---

## 1 answers

### Answer by username_1 on 2019-05-18. Score: 3 | Accepted answer

You can query TIC by Gaia ID. Using the MAST Portal, MAST Catalogs, TESS Input v7, Advanced Search form, I specified:
GAIA ID: 4052922352453886976
and got a single result:
TIC ID (ID):            50559830
RA (ra):                275.945292 (18:23:46.870)
Dec (dec):              -25.672353 (-25:40:20.47)
TESS Mag. (Tmag):       13.579
Version (version):      20180610
UCAC ID (UCAC):         322-168973
2MASS ID (TWOMASS):     18234686-2540204
GAIA ID (GAIA):         4052922352453886976
GAIA G Mag. (GAIAmag):  14.5068

Since the MAST portal currently provides TICv7, the Gaia ID is probably from Gaia DR1.
The TIC release notes say Gaia DR2 data are new in TICv8.

9  GAIA  The matched Gaia DR2 identifier has been updated in TICv8.
  Gaia IDs in TICv8 are included for stars that are found in the Gaia-provided Gaia-2MASS look-up table.
  These identifiers have been updated by the Gaia team from DR1 to DR2, and may not be consistent between TICv7 and TICv8.

> **Comments:**
> **username_0**: From the [Gaia table description](https://gea.esac.esa.int/archive/documentation/GDR2/Gaia_archive/chap_datamodel/sec_dm_main_tables/ssec_dm_gaia_source.html) the `source_id` encodes "...the provenance (data processing centre where it was created)...". Does this mean that each TIC target could correspond to multiple `source_id`s? That is, can multiple Gaia observations be of the same target? With this, the TIC table may only link a single `source_id` and so some `source_id`s may correspond to targets in the TIC table, but may not show up there?  
> **username_1**: If the [TIC paper](https://arxiv.org/abs/1706.00495) and some test queries don't answer that question, try the TESS help desk?  
> **username_0**: Thank you for the reference. For others reading this, from the [TIC Paper](https://arxiv.org/abs/1706.00495), "Gaia IDs in TIC-6 are included for stars which are found in the Gaia-provided Gaia-2MASS look-up table. For TIC stars with more than one associated Gaia magnitude, the ID of the brightest matching Gaia source is provided." So it would seem that multiple Gaia `source_id`s will correspond to a single TIC ID, but only the brightest will be shown. So if the `source_id` is not the brightest one, the above method will not work, and RA/DEC will still be needed (unless I'm missing something).  

---

