The Iris nebula in Cephus (NGC 7023, Caldwell 4) [Explored #79]

A young star throws out gas and matter as it settles down onto the main sequence. It will eventually become a B class giant at about 8-10 solar masses.

 

Another early star throwing off matter can be seen at 5 o'clock down from the central star of the Iris giving off a small cone of bright light/matter.

 

UV light from the star is scattered through the surrounding dust clouds giving a blue colour. the cold dust clouds further out are red-brown in colour.

 

My previous attempt at imaging this nebula using a robotic scope in Grand Mesa Observatory, Colorado is here:

flic.kr/p/2mw1m5c

 

Technical Card

SkyWatcher Esprit 120ED triplet refractor.

SkyWatcher 1.0 x FF with 2 inch IDAS LPS P3 filter

ZWO ASI2600MC;

50 x 180s subs, Gain 100, Offset 25, Temp = -10c.

 

EQ6 pro mount with Rowan belt drives. EQMOD control. Pegasus Astro Focus Cube electronic focuser.

 

Session control; SharpCap 4.0 on laptop with WiFi link to IPad.

Automated plate solving GOTO via ASTAP (4 secs exp at Gain 450)

 

30 dark frames

30 flat frames (electroluminescent panel, 3000ms exposure at Gain 0).

 

Post processed in PixInsight 1.8.9.2.

BlurXterminator and StarXterminator plug-ins used.

 

Light Pollution and Weather:

Clear throughout. I collected 54 subs but discarded the worst 4 as measured by Sub Frame Selector in PixInsight.

SQM (L) was 20.36 - Bortle 4.5

 

 

Polar Alignment:

PoleMaster alignment

Error measured by PHD2= 4.3 arc minute.

RA drift + 0.4 arcsec/min

Dec drift + 0.42 arcsec/min

 

Guiding:

PHD2 guiding with ZWO ASI290mm/Primalucelab

240/60mm guider.

RA RMS error 0.61 arcsec

Dec RMS error 0.66 arcsec

 

Astrometry:

Resolution ............... 0.900 arcsec/px

Rotation ................. -81.757 deg

Focal distance ........... 861.37 mm

Pixel size ............... 3.76 um

Field of view ............ 1d 10' 39.9" x 49' 40.3"

Image center ............. RA: 21 01 22.892 Dec: +68 02 07.47

Done