# How to read hourangles in to Table and SkyCoord via ascii.cds or the like

**URL:** <https://community.openastronomy.org/t/how-to-read-hourangles-in-to-table-and-skycoord-via-ascii-cds-or-the-like/339>\
**Category:** Astropy\
**Created:** [April 17, 2022, 3:00am UTC](https://community.openastronomy.org/t/how-to-read-hourangles-in-to-table-and-skycoord-via-ascii-cds-or-the-like/339 "2022-04-17T03:00:09Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![nealmcb](https://dub1.discourse-cdn.com/flex005/user_avatar/community.openastronomy.org/nealmcb/32/152_2.png) [@nealmcb](https://community.openastronomy.org/u/nealmcb)\
**Post date:** [April 17, 2022, 3:00am UTC](https://community.openastronomy.org/t/how-to-read-hourangles-in-to-table-and-skycoord-via-ascii-cds-or-the-like/339/1 "2022-04-17T03:00:09Z")

</div>

I’m reading in ASCII data like this, where the RA values are in decimal hours:

```auto
data = """Star 3865: expected And, found Psc at B1875 RA= 0.716812, DEC= 29.753839
Star 7751: expected Phe, found Eri at B1875 RA= 1.583496, DEC=-52.227227
Star 10342: expected Per, found And at B1875 RA= 2.089285, DEC= 50.478508
Star 19173: expected Hyi, found Ret at B1875 RA= 4.110955, DEC=-67.498972
"""

```

It seemed good to use a parsing method which allows me to cleanly describe the units involved so the table is easy to turn into `SkyCoord`s later on. So I’m trying

```auto
header = """Byte-by-byte Description of file: data.txt
--------------------------------------------------------------------------------
   Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
   5- 11 I7 --- Index HYG Star number
  23- 25 A3 --- expected expected constellation
  34- 36 A3 --- found HYG constellation
  50- 59 F3.6 hourangle ra Hours of Right Ascension (J2000)
  66- 75 F3.6 deg dec Degrees of declination (J2000)
--------------------------------------------------------------------------------
"""

```

Then I read it in with

```auto
from astropy.table import Table

t = Table.read(header + data, format="ascii.cds")

WARNING: UnitsWarning: 'hourangle' did not parse as cds unit: At col 0, 
Unit 'hourangle' not supported by the CDS SAC standard. If this is meant
 to be a custom unit, define it with 'u.def_unit'. To have it recognized 
inside a file reader or other code, enable it with 'u.add_enabled_units'.
For details, see https://docs.astropy.org/en/latest/units/combining_and_defining.html [astropy.units.core]

```

I picked `hourangle` since it is available as an astropy unit `u.hourangle`  
If instead I use the unit `h`, the table reads in fine, but then I can’t convert it to an angle:

```auto
>>> SkyCoord(t.columns[3].quantity, t.columns[4].quantity )
UnitTypeError: Longitude instances require units equivalent to 'rad', so cannot set it to 'h'.

```

I even tried following the instructions at the page linked to in the error message:

```auto
hourangle = u.hourangle
u.add_enabled_units([hourangle])

```

But I still got the same error.

I assume it is supposed to be easy to read in a table with ra,dec in hourangles, degrees, and convert that to SkyCoords. And it’s hard to believe I’d have to define a custom unit to do that.  
How can I do it?  
Many thanks!