NGC 1512 | An Interacting Galaxy Pair (Kevin Morefield)

NGC 1512 | An Interacting Galaxy Pair

This object pair caught my eye for several reasons. I liked the contrast of the blue cored NGC 1510 and the orange bar on NGC 1512. Also the double ring structure in the core of 1512. But I think the extended blue arms tracing circles around the pair is most interesting. A Galex ultraviolet image shows these arms well and this probably explains why they are almost a pure blue in my image. I will upload a roughly aligned version of the Galex image for comparison.

Cleaned of Red continuum, the Ha data shows almost no activity outside the to core rings. Interestingly the very blue core of 1510 shows the brightest Ha signal! However, the blue still far outshines the Ha there.

There is a quite bright star just outside of the FOV which caused some quite bad reflection/refraction artifacts. These intruded on the galaxy's arms in my initial framing but I couldn't see most it till I integrated 5 hours of excellent Luminance data! I had to reframe twice to get the reflections aways from the galaxy. In the end, I had over 17 hours of Luminance data spread over three framing choices. To make best use of this data I made two Luminance masters; one from the sharpest half of the subs for the galaxy core and another with the subs that were not impacted by the reflection. Next I linear fit the two masters. I then created a mask file that included the cores of the two galaxies and with some feathering. The two masters were combined in Pixelmath with this expression: Luminance_Core * Mask + Luminance_ Full*(1-Mask). This was done linear space and after running BXT on both. It worked! And it felt good not to waste good data.

The blended Luminance master and the RGB master were both stretched using successive GHS stretches. This was the best way to deal with the immense dynamic range this object presents. Displaying those faint arms without saturating the core is not easy!

Original
B
C
Final
D

B

Title: Galex Ultraviolet

Uploaded: ...

C

Title: Ha Cleaned of continuum

Uploaded: ...

D

Description: Contrast

Uploaded: ...

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Status	Advanced success
Started	...
Astrometry.net job	8725434
PixInsight job	M0MY4UV5R2GG65CQLFZKHR6CQLZ9DR2M
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	04h03m55s.804
RA (top/left)	04h02m53s.630
RA (top/right)	04h05m16s.299
RA (bottom/right)	04h04m57s.719
RA (bottom/left)	04h02m35s.747

Dec (center)	-43°22′47″.63
Dec (top/left)	-43°34′37″.50
Dec (top/right)	-43°30′10″.90
Dec (bottom/right)	-43°10′54″.79
Dec (bottom/left)	-43°15′21″.44

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