possible error in RA conversion

[Richard Lee]

Hello

There seems to be an error in AstroImageJ converting RA deg -> RA sexagesimal in DP Coordinate Converter. The conversion error is common to RA input boxes:  J2000 / B1950 / Equatorial

Example: enter 306.07125 converts to 18:04:16.5, should be 20:24:17.1. The Dec conversion is OK, e.g. 33.879167 converts to +33:52:45 (correct)

From Help/About, I'm running AIJ db 3.2.1 / Java 1.7.0_71 (64 bit) on Win 10 PC. Recently installed AIJ and updated to current daily build. Issue persists after downloading new version, power cycling PC etc.

Regards

Richard Lee

[karenacollins]

Hi Richard,

The RA fields must be entered in either decimal or sexagesimal *hours*, so if you divide 306.07125/15=20.40475 and enter
that value, then AIJ gives 20:24:17.1. Does that address the problem you are experiencing?

Karen

[Richard Lee]

Hello Karen

Thanks for getting back so quickly. As you point out, entering RA in hh.hhh format converts to the correct sexagesimal result. Problem solved.. I should read the tooltips where RA / hours clearly stated ..

I tripped over this when configuring CCD DataProcessor for Target Coordinate Source => FITS header RA/DEC (J2000). FITs images are plated solved using TheSkyX Image Link which gives image centre coordinates ra/dec both in dd.ddd format. Just to be sure .. this DP option works with decimal RA / DEC in HH.HHH / DDD.DDD format, IOW I should overwrite the ImageLink RA value by RA/15?

Regards

Richard

----Original message----
From : [hidden email]
Date : 13/11/2017 - 12:09 (GMTST)
To : [hidden email]
Subject : Re: possible error in RA conversion

Hi Richard,

The RA fields must be entered in either decimal or sexagesimal *hours*, so if you divide 306.07125/15=20.40475 and enter
that value, then AIJ gives 20:24:17.1. Does that address the problem you are experiencing?

Karen

---

If you reply to this email, your message will be added to the discussion below:

http://astroimagej.1065399.n5.nabble.com/possible-error-in-RA-conversion-tp897p898.html

To unsubscribe from possible error in RA conversion, click here.
NAML

[karenacollins]

Hi Richard,

I'm not clear exactly what you are meaning when you write "this DP option works with decimal RA / DEC in HH.HHH /
DDD.DDD format, IOW I should overwrite the ImageLink RA value by RA/15"?

The first part about the RA/DEC formatting is correct. However, I'm not clear on "I should overwrite the ImageLink RA
value by RA/15".

AIJ should read the ImageLink plate-solved WCS headers without any problem. I use TSX ImageLink regularly too. However,
if you are copying an RA value from ImageLink that is reported in degrees, you would need to divide it by 15 to give the
correct value in hours before entering into Coordinate Converter RA boxes.

Karen

[Richard Lee]

Hello Karen

As you may have guessed, I was getting completely confused over RA in deg or RA in hour. Your last paragraph explains things perfectly clearly.

Thanks again for bearing with me on this -

Regards

Richard

----Original message----
From : [hidden email]
Date : 14/11/2017 - 05:06 (GMTST)
To : [hidden email]
Subject : Re: possible error in RA conversion

Hi Richard,

I'm not clear exactly what you are meaning when you write "this DP option works with decimal RA / DEC in HH.HHH /
DDD.DDD format, IOW I should overwrite the ImageLink RA value by RA/15"?

The first part about the RA/DEC formatting is correct. However, I'm not clear on "I should overwrite the ImageLink RA
value by RA/15".

AIJ should read the ImageLink plate-solved WCS headers without any problem. I use TSX ImageLink regularly too. However,
if you are copying an RA value from ImageLink that is reported in degrees, you would need to divide it by 15 to give the
correct value in hours before entering into Coordinate Converter RA boxes.

Karen

---

If you reply to this email, your message will be added to the discussion below:

http://astroimagej.1065399.n5.nabble.com/possible-error-in-RA-conversion-tp897p900.html

To unsubscribe from possible error in RA conversion, click here.
NAML