Introduction In this fresh list, Stephen James O'Meara presents 109 new objects for stargazers to observe. Featuring galaxies, clusters and nebulae not covered in previous Deep-Sky Companions books (Messier, Caldwell and Hidden Treasures), the Secret Deep list contains many exceptional objects, including a planetary nebula whose last thermal pulse produced a circumstellar shell similar to the one expected in the final days of our Sun's life; a piece of the only supernova remnant known visible to the unaided eye; the flattest galaxy known; the largest edge-on galaxy in the heavens; the brightest quasar; and the companion star to one of the first black hole candidates ever discovered. This is a wonderful addition to the series and an essential guide for any deep-sky observer. 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 Secret Deep objects visible from my location in Prescott Valley, Arizona.

When possible display all the objects with identical image scale for size comparison

Show that quality images can be obtained with modest-sized high quality equipment

The Cameras

Canon EOS 20Da, 3504 x 2336 pixel CMOS, 8.2 Mpx Canon EOS 60Da, 5184 x 3456 pixel CMOS, 17.9 Mpx

The sizes of the imaging chips in the cameras are the identical APS format. As a result the 60Da has 1.48 times more pixels per inch than the 20Da. When images from the cameras are displayed at the same resolution on a computer screen, the images from the 60Da will be 1.48 times larger. When viewing the photographs obtained with the 60Da will exhibit higher image scale and resolution. The Optical Systems

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 Stellarvue SV80ST-25SV with SFFR80-25 field flattener - 480mm f/6

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. A Bahtinov mask and Nebulosity 3 are also used with the Stellarvue SV80 to check focus with adjustments being made manually. 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 (20Da) or ISO 3200 (60Da) 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 cameras' memory cards. Image acquisition was controlled with a Canon Timer Remote Controller TC-80N3. Basic Image Processing The 30 light-frames were examined and any with bright satellite or airplane trails were discarded. DeepSkyStacker 3.3.2 was used to calibrate and stack the good frames (usually 27 to 30) 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 8-12.

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 100-400mm optical systems were up-sampled to match that of the Takahashi Sky 90 optical system for images obtained with the Canon 20Da. Images obtained with the Canon 60Da are displayed with image scale unchanged at 1.48 times that of the 20Da. 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 6.5 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 better images await the future editions of this album.

Secret Deep

OC: open cluster PN: planetary nebula SG: spiral galaxy GC: globular cluster SR: supernova remnant EG: elliptical galaxy BN: emission nebula IG: irregular galaxy

S NGC/IC/… Type Mag RA Dec Optics Camera

S1 VDB 1 BN - 00h 11.0m +58º 46' SV80 60Da S2 134 SG 10.4 00h 30.4m -31º 15' SV80 60Da S3 488 SG 10.3 01h 21.8m +05º 15' Sky 90 60Da S4 654 OC 6.5 01h 44.0m +61º 53' Sky 90 20Da S5 Cr 463 OC 5.7 01h 45.7m +71º 49' Sky 90 60Da S6 Stock 2 OC 4.4 02h 14.7m +59º 29' Sky 90 60Da S7 936 SG 10.2 02h 27.6m -01º 09' Sky 90 20Da S8 1084 SG 10.7 02h 46.0m -07º 35' Sky 90 60Da S9 1245 OC 8.4 03h 14.7m +47º 14' Sky 90 60Da

S10 1300 SG 10.4 03h 19.7m -19º 25' Sky 90 60Da S11 1342 OC 6.7 03h 31.7m +37º 22' Canon 400 20Da S12 1400 SG 11.0 03h 39.5m -18º 41' Sky 90 60Da S13 1407 EG 9.7 03h 40.2m -18º 35' Sky 90 60Da S14 1491 BN - 04h 03.4m +51º 19' Sky 90 60Da S15 1514 PN 10.9 04h 09.6m +30º 46' Sky 90 60Da S16 1579 BN - 04h 30.2m +35º 16' Sky 90 60Da S17 1750 OC 6 05h 04.3m -23º 44' Sky 90 60Da S18 1758 OC 7.5 05h 04.7m -23º 48' Sky 90 60Da S19 1788 BN - 05h 06.9m -03º 21' Sky 90 60Da S20 1807 OC 7.0 05h 10.8m +16º 31' Sky 90 60Da S21 1817 OC 7.7 05h 12.4m +16º 41' Sky 90 60Da S22 IC 417 BN 8 05h 28.1m +34º 26' Sky 90 20Da S23 1931 BN 10.1 05h 31.4m +34º 15' Sky 90 20Da S24 Cr 70 OC 0.6 05h 35.6m -01º 05' SV80 60Da S25 2022 PN 11.9 05h 42.1m +09º 05' Sky 90 20Da S26 Sh2-276 SR - 05h 52.5m +00º 45' Sky 90 60Da S27 IC 2149 PN 10.7 05h 56.4m +46º 06' Sky 90 60Da S28 2149 BN - 06h 03.5m -09º 44' Sky 90 60Da S29 2170 BN - 06h 07.5m -06º 24' Sky 90 60Da S30 2281 OC 5.4 06h 48.3m +41º 05' Sky 90 60Da S31 2298 GC 9.3 06h 49.0m -36º 00' SV80 60Da S32 2316 BN - 06h 59.7m -07º 46' Sky 90 60Da S33 2343 OC 6.7 07h 08.1m -10º 37' Sky 90 60Da S34 2346 PN 11.8 07h 09.4m -00º 48' Sky 90 60Da

S NGC/IC/… Type Mag RA Dec Optics Camera S35 2359 BN - 07h 18.6m -13º 12' Sky 90 20Da S36 2371-2 PN 11.3 07h 25.5m +29º 29' Sky 90 20Da S37 2420 OC 8.3 07h 38.4m +21º 34' Sky 90 60Da S38 3079 SG 10.9 10h 02.0m +55º 41' Sky 90 20Da S39 3077 IG 9.8 10h 03.3m +68º 44' Sky 90 20Da S40 3166 SG 10.4 10h 13.8m +03º 26' Sky 90 60Da S41 3169 SG 10.2 10h 14.2m +03º 28' Sky 90 60Da S42 3198 SG 10.3 10h 19.9m +45º 33' Sky 90 60Da S43 3226 EG 11.4 10h 23.4m +19º 54' Sky 90 60Da S44 3227 SG 10.3 10h 23.5m +19º 52' Sky 90 60Da S45 3432 SG 11.2 10h 52.5m +36º 37' Sky 90 20Da S46 3675 SG 10.2 11h 26.1m +43º 35' Sky 90 20Da S47 3893 SG 10.5 11h 48.6m +48º 43' Sky 90 60Da S48 3953 SG 10.1 11h 53.8m +52º 20' Sky 90 20Da S49 4036 SG 10.7 12h 01.4m +61º 54' Sky 90 60Da S50 4051 SG 10.2 12h 03.2m +44º 32' SV80 60Da S51 4111 SG 10.7 12h 07.1m +43º 04' Sky 90 20Da S52 4147 GC 10.3 12h 10.1m +18º 32' SV80 60Da S53 4293 SG 10.4 12h 21.2m +18º 23' SV80 60Da S54 4414 SG 10.1 12h 26.4m +31º 13' Sky 90 20Da S55 4435 SG 10.8 12h 27.7m +13º 05' Sky 90 20Da S56 4438 SG 10.2 12h 27.8m +13º 01' Sky 90 20Da S57 4450 SG 10.1 12h 28.5m +17º 05' SV80 60Da S58 4461 SG 11.2 12h 29.0m +13º 11' Sky 90 20Da S59 3C 273 Quasar 12.4 12h 29.1m +02º 03' SV80 60Da S60 4473 EG 10.2 12h 29.8m +13º 26' Sky 90 20Da S61 4477 SG 10.4 12h 30.0m +13º 38' Sky 90 20Da S62 4636 EG 9.5 12h 42.8m +02º 41' SV80 60Da S63 4665 SG 10.5 12h 45.1m +03º 03' SV80 60Da S64 4753 IG 9.9 12h 52.4m -01º 12' SV80 60Da S65 4762 SG 10.3 12h 52.9m +11º 04' Sky 90 20Da S66 5033 SG 10.2 13h 13.4m +36º 36' Sky 90 20Da S67 5195 SG 9.6 13h 30.0m +47º 16' Canon 400 20Da S68 5466 GC 9.0 14h 05.4m +28º 32' Sky 90 20Da S69 5846 EG 10.0 15h 06.4m +01º 36' SV80 60Da S70 5907 SG 10.3 15h 15.9m +56º 20' Sky 90 20Da S71 IC 4593 PN 10.7 16h 11.7m +12º 04' Sky 90 20Da S72 6144 GC 9.0 16h 27.2m -26º 01' Sky 90 20Da S73 6207 SG 11.6 16h 43.1m +36º 50' Canon 400 20Da

S NGC/IC/… Type Mag RA Dec Optics Camera S74 6229 GC 9.4 16h 46.9m +47º 32' Sky 90 20Da S75 6293 GC 8.2 17h 10.2m -26º 35' SV80 60Da S76 6309 PN 11.5 17h 14.1m -12º 55' SV80 60Da S77 6356 GC 8.2 17h 23.6m -17º 49' SV80 60Da S78 6522 GC 8.3 18h 03.6m -30º 02' SV80 60Da S79 6528 GC 9.6 18h 04.8m -30º 03' SV80 60Da S80 6563 PN 11.0 18h 12.1m -33º 52' SV80 60Da S81 6589 BN - 18h 16.9m -19º 47' SV80 60Da S82 6595 BN - 18h 17.1m -19º 52' SV80 60Da S83 6638 GC 9.2 18h 30.9m -25º 30' Sky 90 20Da S84 6664 OC 7.8 18h 36.5m -08º 11' SV80 60Da S85 6717 GC 8.4 18h 55.1m -22º 42' SV80 60Da S86 6751 PN 11.9 19h 05.9m -06º 00' SV80 60Da S87 6755 OC 7.5 19h 07.8m +04º 16' SV80 60Da S88 6756 OC 10.6 19h 08.7m +04º 42' SV80 60Da S89 6778 PN 11.9 19h 18.4m -01º 36' SV80 60Da S90 6781 PN 11.4 19h 18.5m +06º 32' Sky 90 20Da S91 6804 PN 12.2 19h 31.6m +09º 13' SV80 60Da S92 6811 OC 6.8 19h 37.2m +46º 22' SV80 60Da S93 Cygnus X-1 Star 8.8 19h 58.4m +35º 12' SV80 60Da S94 O'Meara 3 Asterism - 20h 05.3m +47º 32' SV80 60Da S95 6891 PN 10.5 20h 15.2m +12º 42' SV80 60Da S96 6894 PN 12.3 20h 16.4m +30º 34' SV80 60Da S97 IC 1318(a) BN - 20h 16.6m +41º 49' SV80 60Da S98 6905 PN 11.1 20h 22.4m +20º 06' SV80 60Da S99 6910 OC 6.6 20h 23.2m +40º 47' SV80 60Da

S100 6939 OC 7.8 20h 31.5m +60º 40' Sky 90 20Da S101 7026 PN 10.9 21h 06.3m +47º 51' SV80 60Da S102 7048 PN 12.2 21h 14.2m +46º 17' SV80 60Da S103 7129 BN - 21h 42.8m +66º 06' Sky 90 20Da S104 7160 OC 6.1 21h 53.7m +62º 36' SV80 60Da S105 7209 OC 7.7 22h 05.8m +46º 29' Sky 90 20Da S106 7354 PN 12.2 22h 40.3m +61º 17' SV80 60Da S107 7510 OC 7.9 23h 11.1m +60º 34' SV80 60Da S108 7538 BN - 23h 13.5m +61º 31' SV80 60Da S109 7790 OC 8.5 23h 58.4m +61º 12' SV80 60Da