NGC7023 Iris Nebula

mouseover for annotation

view full size

2013/06/08 - The nights are very short this time of year, so I spent five nights gathering data of this nebula to get the brown color. It wasn't easy under a SQM 19.14-19.55 sky. Seeing was between 1.97" and 2.84".

The Iris Nebula, also NGC 7023 and Caldwell 4, is a bright reflection nebula and Caldwell object in the constellation Cepheus. NGC 7023 is actually the cluster within the nebula, LBN 487, and the nebula is lit by a magnitude +7 star, SAO 19158. It shines at magnitude +6.8. It is located near the Mira-type variable star T Cephei, and near the bright magnitude +3.23 variable star Beta Cephei (Alphirk). It lies 1,300 light-years away and is six light-years across.

Object information
Name : NGC7023 Iris Nebula
Type : Nebula
Constellation : Cepheus
Distance : 1.300 light-year
Apparent dimensions : 18' x 18'
Apparent magnitude : 6.80

Image information
Image date : 2013/06/08, 2013/06/07, 2013/06/06, 2013/06/05, 2013/06/04
Right ascension : 21:1:36.987
Declination : 68°9' 44.05"
Focal length : 1381.73 mm
Focal ratio : f/5.44
Image resolution : 0.806 arcsec/pixel
Field of view : 44' 14.5" x 33' 11.9"
Sky quality : 19.14-19.55 mag/arcsecond2
Guiding rms : 0.3 arcsec
Sensor temperature : -25°C
Light frames : 15 hours total exposure time
30x 600 sec. luminance unbinned
20x 600 sec. RGB unbinned
Image acquisition with CCDAutoPilot and Maxim DL
Auto-guiding with Maxim DL
Auto-focusing with FocusMax
Bias frames : 100x unbinned
Dark frames : None
Flat frames : 12x luminance unbinned
12x RGB unbinned
Automated sky twilight flats with CCDAutoPilot
Processing : PixInsight for calibration, alignment and integration.
Adobe Photoshop CS6 for final touch.

Equipment information
Telescope : Robtics 10" 2000mm f/8 Ritchey Chretien
Corrector : Astro-Physics CCDT67 Focal Reducer
Focuser : Moonlite CS Ritchey Chretien focuser with high resolution stepper motor
Mount : ASA DDM60 Pro direct drive german equatorial mount controlled with AutoSlew
Camera : QSI 683wsg-8 cooled CCD camera with Kodak KAF-8300 sensor and Off Axis Guide (OAG) port
Guidecamera : Starlight Xpress Lodestar autoguider
Filters : Astrodon Tru-Balance E-Series LRGB & Astrodon 3nm H-α, 3nm O-III, 3nm S-II and 3nm N-II
Observatory site : Etten-Leur, The Netherlands