New Feature : Deep Sky Image Annotation

[Jean-Francois]

Hello,

I come back from my tests with 2 telescopes (and cameras) mounted in parallel on my mount.
But ... I forget to unplug the SSD drive from the mini computer installed on the Newton telescope ... so I have now no image to show.

The summary ... the annotation after plate solve works very good on different catalogs ... except my HD star catalog.
Fast all the stars from my catalog are not in the correct place.
Here below the first 5 HD stars generated by the VizieR database.
But now I think that I found why ... can you find it too ?

Good night,
Jean-Francois

#
# VizieR Astronomical Server vizier.cds.unistra.fr
# Date: 2022-02-20T18:06:13 [V1.99+ (14-Oct-2013)]
# In case of problem, please report to: cds-question@unistra.fr
#
#
#Coosys J2000: eq_FK5 J2000
#INFO votable-version=1.99+ (14-Oct-2013)
#INFO -ref=VIZ621281b816a169
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#INFO queryParameters=18
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#-nav=cat:III/135A&tab:{III/135A/catalog}&key:source=III/135A/catalog&HTTPPRM:&&-ref=VIZ621281b816a169&-file=.&-out.add=_r&-out.add=_RAJ,_DEJ&-sort=_r&-oc.form=sexa&-c.r= 2&-c.geom=r&-order=I&-out.form=verb&-out=HD&-out=DM&-out=RAB1900&-out=DEB1900&-out=q_Ptm&-out=Ptm&-out=n_Ptm&-out=q_Ptg&-out=Ptg&-out=n_Ptg&-out=SpT&-out=Int&-out=Rem&-out=Simbad&-ignore=Simbad=*&Simbad=Simbad&-out=_RA.icrs&-out=_DE.icrs&-out=Tycho&Tycho=Tycho&-meta.ucd=2&-meta=1&-meta.foot=1&-usenav=1&-bmark=POST&-out.max=50&-out.form=HTML Table&-c.eq=J2000&-c.u=arcmin&
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#RESOURCE=yCat_3135
#Name: III/135A
#Title: Henry Draper Catalogue and Extension (Cannon+ 1918-1924; ADC 1989)
#Coosys B1900_1900.000: eq_FK4 B1900
#Table III_135A_catalog:
#Name: III/135A/catalog
#Title: Henry Draper catalogue
#Column _RAJ2000 (F8.4) Right ascension (FK5, Equinox=J2000.0) at Epoch=J1900. (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services) [ucd=pos.eq.ra]
#Column _DEJ2000 (F8.4) Declination (FK5, Equinox=J2000.0) at Epoch=J1900. (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services) [ucd=pos.eq.dec]
#Column HD (I6) [1/272150]+ Henry Draper Catalog (HD) number [ucd=meta.id;meta.main]
#Column Ptm (F5.2) ? Photovisual magnitude (2) [ucd=phot.mag;em.opt.V]
#Column SpT (A3) Spectral type [ucd=src.spType]
#Column _RA.icrs (A10) Right ascension (ICRS) at Epoch=J1900. (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services) [ucd=pos.eq.ra]
#Column _DE.icrs (A9) Declination (ICRS) at Epoch=J1900. (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services) [ucd=pos.eq.dec]
_RAJ2000|_DEJ2000|HD|Ptm|SpT|_RA.icrs|_DE.icrs
deg|deg| |mag| |"hs"|"ds"
--------|--------|------|-----|---|----------|---------
001.2961|+67.8401| 1| 7.70|K0 |00 05 11.1|+67 50 24
001.2907|+57.7734| 2| 8.60|F5 |00 05 09.8|+57 46 24
001.2871|+45.2234| 3| 6.51|A0 |00 05 08.9|+45 13 24
001.2845|+30.3235| 4| 8.40|F0 |00 05 08.3|+30 19 24
001.2811| +2.3735| 5| 9.00|G5 |00 05 07.5|+02 22 25

[Jean-Francois]

Hello,

I copy the pictures from last night.
I do with a RASA8" + QHY-183 and with a Newton+2.8 reducer + QHY-174.

All the faints NGC or IC are good positioned.
But the HD stars from my catalog are not.

I used the "Save images with annotation" ... (very good fonction).

Capture_annotation_Newton_1.jpg (222 KiB) Viewed 5311 times

Capture_annotation_RASA_1.jpg (195.31 KiB) Viewed 5311 times

Capture_annotation_RASA_2.jpg (142.02 KiB) Viewed 5311 times

Regards,
Jean-Francois

[admin]

Hi Jean-Francois,

interesting - I can see that the ones that are incorrectly placed are not all offset in the same direction - rather the errors seem to be a bit random. Could it possibly be a rounding error in the co-ordinates - either in the catalog file or in the way that SharpCap is reading them?

I don't think it's an issue in your case, but there are situations where the positioning may not be correct - SharpCap uses a linear model for the mapping between pixel co-ordinates and sky co-ordinates, so in very large fields of view, or near the celestial poles, you will have errors.

cheers,

Robin

[procyon12]

Hi,

Jean-Francois, as you know already, your catalog is wrong - I don't know why, but you must find it out

I solved your Capture_annotation_Newton_1.jpg with SC (as I wrote, ANSVR) it worked. Then I solved it under an Ubuntu VM using the Ubuntu platesolve package. This worked too. Following is one result, so I think distorsion is not the reason.

Capture_annotation_Newton_1-indx.jpg (408.33 KiB) Viewed 5299 times

In the left upper corner is HD98388, red and green marked ... Also opening this image (having WCS) in CDC shows all the stars right, centered. From CDC, the coordinates of HD98388 are:

Apparent RA: 11h20m16.241s DE:+13°16'07.25"
Mean of the date RA: 11h20m15.724s DE:+13°16'09.68"
Astrometric J2000 RA: 11h19m06.394s DE:+13°23'26.70"
Ecliptic L: +165°38'49" B:+08°16'05"
Galactic L: +240°50'03" B:+64°25'58"

If you compare with your catalog, are there wrong entries?

Cheers, Christian

[Jean-Francois]

Hello Robin and Christian,

Thanks for your comments.
Random errors ... no.
Rounding errors ... could be. But I do not change the coordinate format from VizieR catalog.
Systematic errors ... no. It is no common movement of all the stars in the field.

Concering the star HD98388, here the output from VizieR (=SharpCap catalog):
169.8063|+13.3865| 98388| 7.08|F8 |11 19 13.5|+13 23 11
Compared to your calculation: Astrometric J2000 RA: 11h19m06.394s DE:+13°23'26.70".

If you read the catalog file header (preceding message), you can find the following:
#Column _RAJ2000 (F8.4) Right ascension (FK5, Equinox=J2000.0) at Epoch=J1900. (computed by VizieR, not part of the original data.
#Column _DEJ2000 (F8.4) Declination (FK5, Equinox=J2000.0) at Epoch=J1900. (computed by VizieR, not part of the original data.

The point is on "at Epoch=J1900" !
I can start a calculation with Tycho ... here (top from VizieR, bottom from Tycho catalog, but calculated by VizieR):

Catalog_HD98388.jpg (172.53 KiB) Viewed 5292 times

From Tycho, the coordinates are the same as the Astrometric J2000.

OK what next ?
For example ... to measure the distance between the annotation and the real star and compare with the coordinates differences.
RA diff = 7.11 s and DEC diff = -15.7''

Or ... I forget HD catalog and I generate a PPM catalog

Regards,
Jean-Francois

[Jean-Francois]

Hello,

Here the last result with the image annotation function ...

Last Monday I try to capture 4 different occultations. Between 2 occultations, I try to image the JWST.
I used a website of the JPL for the ephemeris and then I did a GOTO at that position.
At the same time I used the image annotation with my last catalog ... PPM (that works, not like my HD catalog).

I used the Live Stack, the image is 48 individual images of 20 seconds.
Equipment: Newton 10" FD4 with reducer to FD2.8, QHY-174-GPS.

JWST_withAnnotations.jpg (290.77 KiB) Viewed 5235 times

Regards,
Jean-Francois

[procyon12]

Nice work, Jean-Francois

Christian

[Jean-Francois]

Hello,

Robin, Menno and Christian, thanks for your comments.

Concerning the HD catalog ... I have no idea what to do. I will try to contact somebody at the observatory of Paris for some help.
In my PPM catalog, some stars are in the HD catalog too, but not all the HD stars.

Regards,
Jean-Francois

[admin]

Hi Jean-Francois,

does the data you collect have correct JNOW (or J2022, or whatever) co-ordinates? If so then you can transform them using Python and AstroPy

Code: Select all

from astropy.coordinates import SkyCoord
import astropy.units as u
from astropy.coordinates import ICRS, Galactic, FK4, FK5, ITRS, TETE
from astropy.time import Time
jnow= SkyCoord(ra, dec, unit = (u.deg), frame=TETE(obstime=Time('2022-01-01')))
j2000 = jnow.transform_to(ICRS)
print(j2000)

I think that's right - TETE is 'true equator, true ecliptic' (basically JNOW) for a given date. ICRS is J2000 down to a tiny fraction of an arc second.

cheers,

Robin

[Jean-Francois]

Hello Robin,

Yes, it should be possible to convert the coordinate from one system to the other.

From the VizieR database, the HD catalog export was following:
#Column _RAJ2000 (F8.4) Right ascension (FK5, Equinox=J2000.0) at Epoch=J1900. (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services) [ucd=pos.eq.ra]
#Column _DEJ2000 (F8.4) Declination (FK5, Equinox=J2000.0) at Epoch=J1900. (computed by VizieR, not part of the original data ...

The additional question ... if calculated for Epoch=J1900 ... means with or without proper motion ? ... 100 year displacement can be seen on some stars.

Regards,
Jean-Francois