Introduction Upon completing a visual or photographic program of the 110 Messier deep-sky objects, astronomers often wonder "what next?" John Dreyer's NGC catalog contains 7840 objects and his IC supplements added an additional 5386 objects - indeed a formidable list from which to choose. Fortunately a number of astronomy enthusiasts have taken up this challenge and there are now over a half dozen lists of select deep-sky objects to explore. For Northern Hemisphere astronomers a list worth exploring is the Royal Astronomical Society of Canada's Finest NGC Objects. Compiled by Alan Dyer, the list comprises some of the best objects not in Messier's list, such as the Double Cluster, the North America Nebula and the Sculptor Galaxy. The list contains 48 spiral galaxies, 24 planetary nebula, 12 bright nebula, 12 open star clusters, 8 elliptical galaxies, 3 supernova remnants, 2 irregular galaxies and 2 globular star clusters. Being Canada-centric, all the objects in the list are visible from all locations in the contiguous United States. Indeed the RASC Finest NGC Objects are worthy targets for both visual and photographic programs. This second album of digitally acquired images focuses on RASC's Finest NGC Objects. My astrophotography efforts began in 1975 but my ability to obtain acceptable images was hampered by the need for lots of equipment and materials to process film and make final prints and lack of time to adequately develop the skills required. That situation changed dramatically in 2004 when I purchased a Canon EOS 20D digital single lens reflex camera. Relatively quickly, the resulting images began to meet the quality standards I had set for myself and I began a concerted program of deep-sky astrophotography. Three books provided some of my inspiration:

Atlas of Deep-Sky Splendors, Hans Vehrenberg, 1971. The Messier Album, John H. Mallas and Evered Kreimer, 1978. The Cambridge Deep-Sky Album, Jack Newton and Philip Teece, 1983.

Goals

Photograph all the RASC Finest NGC Objects When possible display all the objects with identical image scale for size

comparison Show that quality images can be obtained from modest-sized high

quality equipment The Cameras

Canon EOS 20D Canon EOS 20Da

The cameras have the identical 3504 x 2336 pixel CMOS imaging chip. The Optical Systems

Canon EF 180mm f3.5L Macro USM Canon EF 100-400mm f/4.5-5.6L IS USM set at 400mm f/5.6 Takahashi Sky 90 with 0.8X focal reducer/field flattener - 405mm f/4.5

The Mounts

Vixen GPDX equatorial mount with SkySensor 2000 on JMI Wheeley Bars

Software Bisque Paramount MX equatorial mount on a permanent pier controlled by TheSkyX Pro and an Apple MacBook Pro laptop computer.

Focusing Initially focusing was done manually while observing a star through a Canon Angle Finder C at 2.5x magnification. The quality of focus was checked by examining a test image on the camera's LCD screen. Unfortunately image focus varied significantly, resulting in refocusing and second or even third images being acquired. Eventually a JMI Motofocus and a Bahtinov mask were added to the Sky 90 optical system. Focus was achieved by observing the Bahtinov diffraction pattern on the computer screen using Stack Labs' Nebulosity 3. This focusing

method is vastly superior to the manual method and the need to repeat image acquisition was eliminated. Image Acquisition The basic image acquisition scheme was to obtain 5 dark-frames, then 30 light-frames and finally 5 more dark-frames, yielding an image set of 10 dark-frames and 30 light-frames for calibrating and stacking. Exposure duration of each frame was 1 minute at ISO 1600 with a 10-second delay between exposures and a 5-second delay from sequence initiation and the first exposure. No bias or flat frames were used. Images were saved as highest quality JPEG files on the camera's Compact Flash card. Image acquisition was controlled with a Canon Timer Remote Controller TC-80N3. Basic Image Processing DeepSkyStacker 3.3.2 was used to calibrate and stack the frames from each image set. The final raw stacked image file was saved as a 32-bit TIFF file. Image enhancement and optimization was performed with Adobe Photoshop CS2. First the image file Mode was changed to 16-bit. While examining the upper right corner of the image, Levels was used to adjust the RGB black point such that R=G=B at a value of 10-15.

Using Curves, the low intensity nebulosity was enhanced while not 'blowing out' bright zones or causing the black background to lighten significantly by setting Curves set points approximately as shown in the figure above. Any resulting vignetting in background sky intensity was 'neutralized' using techniques similar to those described in "Fixing Vignetting in Astrophotos", Sean Walker, Sky & Telescope, September 2001 and the book Photoshop Astronomy by R. Scott Ireland. Finally a modest Unsharp Mask (amount: 100%, radius: 1.0 pixel, threshold: 3 levels) was applied. The image scale of the three optical systems was determined using Adobe Photoshop CS2 and Voyager 4 Dynamic Sky Simulator. Then the image scale of the images from the Canon EF 180mm and Canon EF 100-400mm optical systems were up-sampled to match that of the Takahashi Sky 90 optical system. Images were then appropriately cropped and combined to make the album pages with all the objects at the same image scale for direct comparison. Final Thoughts The images in the album were acquired over a period of 3.5 years with continuous improvement in equipment, techniques and skills. I am well aware that a number of images could be significantly improved and better photographs will be acquired in the future. In addition, a number of the planetary nebula are essentially 'stellar' in appearance and require significantly greater focal length and image scale yielded by larger OTAs to show detail. But 'perfection' can often be the enemy of 'finishing' so those new images await the second edition of this album.

RASC Finest NGC Objects

PN: planetary nebula IG: irregular galaxy A Canon 180mm BN: diffuse nebula OC: open cluster B Canon 100-400mm SG: spiral galaxy GC: globular cluster C Sky 90 EG: elliptical galaxy SR: supernova remnant

R NGC Type Optics R NGC Type Optics R NGC Type Optics 1 7009 PN C 38 2655 SG C 75 4361 PN C 2 7293 PN C 39 2683 SG C 76 4216 SG C 3 7331 SG C 40 2841 SG C 77 4388 SG C 4 7635 BN C 41 3079 SG C 78 4438 SG C 5 7789 OC C 42 3184 SG C 79 4517 SG C 6 185 EG C 43 3877 SG C 80 4526 EG C 7 281 BN C 44 3941 EG C 81 4535 SG C 8 457 OC C 45 4026 SG C 82 4567/8 SG C 9 663 OC C 46 4088 SG C 83 4699 SG C 10 IC 289 PN C 47 4157 SG C 84 4762 SG C 11 7662 PN C 48 4605 SG C 85 5746 SG C 12 891 SG C 49 3115 EG C 86 5466 GC C 13 253 SG C 50 3242 PN C 87 5907 SG C 14 772 SG C 51 3003 SG C 88 6503 SG C 15 246 PN C 52 3344 SG C 89 6543 PN C 16 936 SG C 53 3432 SG C 90 6210 PN C 17 869/84 OC C 54 2903 SG C 91 6369 PN C 18 1023 EG C 55 3384 EG C 92 6572 PN C 19 1491 BN C 56 3521 SG C 93 6633 OC C 20 1501 PN C 57 3607 EG C 94 6712 GC C 21 1232 SG C 58 3628 SG B 95 6781 PN C 22 1535 PN C 59 4111 SG C 96 6819 OC C 23 1514 PN C 60 4214 IG C 97 6826 PN C 24 1931 BN C 61 4244 SG C 98 6888 SR C 25 1788 BN C 62 4449 IG C 99a 6960 SR A 26 1973+ BN C 63 4490 SG C 99b 6992/5 SR A 27 2022 PN C 64 4631 SG C 100 7000 BN A 28 2024 BN C 65 4656/7 SG C 101 7027 PN C 29 2194 OC C 66 5005 SG C 102 6445 PN C 30 2371/2 PN C 67 5033 SG C 103 6520 OC C 31 2392 PN C 68 4274 SG C 104 6818 PN C 32 2237+ BN C 69 4414 SG C 105 6802 OC C 33 2261 NN C 70 4494 EG C 106 6940 OC C 34 2359 BN C 71 4559 SG C 107 6939 OC C 35 2440 PN C 72 4565 SG C 108 6946 SG C 36 2539 OC C 73 4725 SG C 109 7129 BN C 37 2403 SG C 74 4038/9 SG C 110 40 PN C