<p>You need a model for the motion of the Sun with respect to the Milky Way centre. You then have to subtract the component of this that is resolved towards the galaxy in question.</p>

<p>The solar motion around the Galaxy is somewhat uncertain, but is roughly (11, 240, 7) km/s when expressed as a vector aligned with Galactic coordinates (i.e. towards the Galactic centre, tangential to the Galactic centre and perpendicular to the Galactic disk). </p>

CC BY-SA 3.0
2016-03-30T11:15:12.027Z
I'm still not entirely sure what I need to do, is there an explicit formula or method for the correction?
R Thompson
CC BY-SA 3.0
2016-03-28T13:26:41.837Z
2016-03-28T13:26:41.837Z
ProfRob
<p>I'm currently trying to collect the data to run an N-body simulation for 11 of the galaxies in the Local Group where proper motions are known, however I don't understand how to get the required line of sight velocities for the simulation.</p>

<p>I have redshift data from NED for the required galaxies, however by judging what sources tell me, this won't be the required information for the simulation due to our motion around the Milky way's galactic centre.</p>

<p>For example, one source has given the NED redshift as 229 km/s for Carina Dwarf, but the corrected line of sight velocity is 14.3 km/s.</p>

<p>Does anybody know how to convert these redshifts into the desired corrected versions?</p>

<p>Thanks!!</p>

<galaxy><redshift><galaxy-cluster><velocity>
How do I modify redshifts to gain corrected line of sight velocities?
R Thompson
# How do I modify redshifts to gain corrected line of sight velocities?

(Asked by: username_0 on 2016-03-27)

I'm currently trying to collect the data to run an N-body simulation for 11 of the galaxies in the Local Group where proper motions are known, however I don't understand how to get the required line of sight velocities for the simulation.

I have redshift data from NED for the required galaxies, however by judging what sources tell me, this won't be the required information for the simulation due to our motion around the Milky way's galactic centre.

For example, one source has given the NED redshift as 229 km/s for Carina Dwarf, but the corrected line of sight velocity is 14.3 km/s.

Does anybody know how to convert these redshifts into the desired corrected versions?

Thanks!!

**Tags:** galaxy, redshift, galaxy-cluster, velocity


---

## 1 answers

### Answer by username_1 on 2016-03-28. Score: 2 | Accepted answer

You need a model for the motion of the Sun with respect to the Milky Way centre. You then have to subtract the component of this that is resolved towards the galaxy in question.

The solar motion around the Galaxy is somewhat uncertain, but is roughly (11, 240, 7) km/s when expressed as a vector aligned with Galactic coordinates (i.e. towards the Galactic centre, tangential to the Galactic centre and perpendicular to the Galactic disk).

> **Comments:**
> **username_0**: I'm still not entirely sure what I need to do, is there an explicit formula or method for the correction?  

---

