Position of MSH 15-5-02, MSH 15-52, HESS J1514-591

cdeil commented 6 years ago

I wonder if we have the correct position for the source that goes by the names of MSH 15-5-02, MSH 15-52, HESS J1514-591 in gamma-cat.

It's this one:

The current position we have is this:

  - ra: 228.32080078125
  - dec: -59.08169937133789
  - pos_ra: 228.52915954589844
  - pos_dec: -59.157501220703125

The ra/dec comes from the SIMBAD position for MSH 15-5-02 from input/sources/tev-000079.yaml:

pos:
  simbad_id: MSH 15-5-02
  ra: 228.3208
  dec: -59.0817

The pos_ra/pos_dec comes from the HESS J1514-591 measurement in gamma-cat/input/data/2005/2005A%26A...435L..17A/tev-000079.yaml

pos:
  ra: {val: 15h14m7s, err: 0h0m21s, err_sys: 20s}
  dec: {val: -59d9m27s, err: 11s, err_sys: 20s}

I double-checked the values in the paper. That is the correct base-fit position from the elongated Gaussian fit in http://adsabs.harvard.edu/abs/2005A%26A...435L..17A .

I'm aware the situation is complex and that there is https://arxiv.org/abs/1709.01422, but I still wonder if the positions we have now in gamma-cat, but also if the ones given in SIMBAD make sense or not.

Here are all relevant positions:

>>> from astropy.coordinates import SkyCoord
>>> msh1 = SkyCoord.from_name('MSH 15-5-02')
>>> msh1
<SkyCoord (ICRS): (ra, dec) in deg
    (228.320833, -59.0816667)>
>>> msh2 = SkyCoord.from_name('MSH 15-52')
>>> msh2
<SkyCoord (ICRS): (ra, dec) in deg
    (228.529167, -59.1575)>
>>> hess_paper = SkyCoord('15h14m7s -59d9m27s')
>>> hess_paper
<SkyCoord (ICRS): (ra, dec) in deg
    (228.52916667, -59.1575)>
>>> hess_simbad = SkyCoord.from_name('HESS J1514-591')
>>> hess_simbad
<SkyCoord (ICRS): (ra, dec) in deg
    (228.320833, -59.0816667)>
>>> psr = SkyCoord.from_name('PSR B1509-58')
>>> psr
<SkyCoord (ICRS): (ra, dec) in deg
    (228.4775, -59.1375)>
>>> snr = SkyCoord.from_name('SNR G320.3-01.1')
>>> snr
<SkyCoord (ICRS): (ra, dec) in deg
    (228.320833, -59.0816667)>

The position of HESS J1514-591 in the paper and in SIMBAD doesn't agree:

>>> hess_paper.separation(hess_simbad)
<Angle 0.1310878 deg>

The hess_simbad position matches msh1 and snr:

>>> hess_simbad.separation(msh1)
<Angle 0. deg>
>>> hess_simbad.separation(snr)
<Angle 0. deg>

The hess_paper position matches msh2 almost perfectly:

>>> hess_paper.separation(msh2)
<Angle 1.70893319e-07 deg>

The separation between those two positions is 0.13 deg:

>>> msh1.separation(msh2)
<Angle 0.13108794 deg>

As expected, neither coincides with the pulsar:

>>> msh1.separation(psr)
<Angle 0.09791187 deg>
>>> msh2.separation(psr)
<Angle 0.03319725 deg>

I'm not able to find the entry for msh2 in SIMBAD directly, this resolves to msh1!? http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HESS+J1514-591

Bottom line: I think we should consider changing common_name from MSH 15-5-02 to MSH 15-52 in gamma-cat, or at least change the position in input/sources/tev-000079.yaml from msh1 to msh2.

Thoughts?

cdeil commented 6 years ago

I figured out just now why the SkyCoord.from_name calls for MSH 15-5-02 and MSH 15-52 give different results.

They always resolve to the same source in SIMBAD, the SNR: http://simbad.u-strasbg.fr/simbad/sim-id?Ident=MSH%2015-52#lab_ident

But in NED MSH 15-52 resolves to the pulsar http://ned.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=MSH%2015-52 which I think is an old pulsar position measurement, because it's different from the pulsar position on SIMBAD: http://simbad.u-strasbg.fr/simbad/sim-id?Ident=PSR%201509-58 and MSH 15-5-02 doesn't resolve at all in NED.

SkyCoord.from_name queries http://cds.u-strasbg.fr/cgi-bin/Sesame and I think the default "all" mode means NED first. That explains the positions obtained above.

That still leaves the question what position to put for this TeV source in gamma-cat. I think my preference would be to use the best-fit position from http://adsabs.harvard.edu/abs/2005A%26A...435L..17A and to leave comments explaining about the MSH names and positions.

cdeil commented 6 years ago

I've made a commit with changes here: acf4947 I'm reasonably happy with this, so merging now. Discussion via email with Michelle, Yves and Konrad is still ongoing, if it concludes in a different way or someone else speaks up here we can always make another commit.

I did change the common_name to "MSH 15-52", putting the previous "MSH 15-5-02" under other_names. It seems that "MSH 15-52" is the "modern name" used in Fermi-LAT and HESS papers. From the original MSH catalog paper it isn't clear what the correct name should be, they do use "15-52" with an italic "2" sometimes, sometimes there is a space between the 5 and 2.

For the position, I did put the best-fit position from http://adsabs.harvard.edu/abs/2005A%26A...435L..17A , avoiding the issue concerning complex morphology / counterpart catalog positions for this source. I also checked the upcoming HGPS paper that contains a 3-Gauss morphology model. The centroid is almost identical with the one from 2005A%26A...435L..17A, i.e. what we have now in gamma-cat.

What we can't change is the CTA first data challenge, which used gamma-cat. It will forever have MSH 15-52 at ~0.1 offset from the true TeV source position. Oh well. :-) See here

gammapy / gamma-cat

Position of MSH 15-5-02, MSH 15-52, HESS J1514-591 #203