How to Find:

When I first tried to locate M104 I used a star chart and my viewfinder to hop from star to star.  While star hopping is a good way to learn your way around the sky, this process is time consuming and frustrating to say the least.  Sometimes I found what I was looking for, but most times I did not.  I find that setting circles are far more powerful tools than many give them credit for.  The main complaint with setting circles is that your scope must be perfectly polar aligned in order to obtain any degree of accuracy (which will still vary as you move across the sky).  I find that this is expecting too much of both the scope and the observer.  My preferred technique is to achieve a good polar alignment and then set the setting circles to a bright star of known RA. and Declination near the object I am searching for.  The closer the bright star is to the sought after object, the more accurate the setting circles.   The size and quality of the setting circles and mount are another variable that should be taken into account when you are thinking about accuracy.  The declination circle once properly set, need never be reset unless it was moved by accident. 

To set your Declination circle (fork mounted Schmidt Cassegrain types ) simply turn your scope so it is parallel to the fork arms so that if you spin the scope on its RA. axis you don't see the scope barrel wobble.  Loosen the Dec. axis finger screws and set the Dec. circle to 90°, then retighten making sure the circle does not move as you apply tension.  This 90° mark should mean that your scope is pointing towards Polaris if you are polar aligned.  Most equatorial type mounts found on reflectors or refractors, the Dec. circle is not adjustable, therefor you must trust the manufacturer.   RA. circles can be freely rotated and are marked in increments of 5 minutes of RA.  On my scope the outer markings (numbers increase counterclockwise) represent the RA. circle for the northern hemisphere, and the inside markings (numbers increase clockwise) represent the RA. circle for the southern hemisphere.

                                               Maps generated by Earth Centred Universe.

Start your clock drive, if you don't have one you will have to constantly compensate for the Earth's rotation manually (nearly impossible while setting the circles).   Once you have found a bright star of known RA. and Declination (you need a star chart or observers guide to determine this), and have it centred it in your eyepiece, turn the RA. circle to this star's RA. co-ordinate (remember outside circle for you northerners).   In the case of M104, this alignment star is Delta Corvus (RA.= 12:29.9 Dec.= -16° 31').   After you have set the RA. circle to this co-ordinate, check to see where your Dec. circle is reading in relation to the star's Dec. co-ordinate.  If your circle is reading +1 or -1 degree from the star's co-ordinate, compensate by that amount when you move the scope to the new co-ordinates of M104 (don't adjust the Dec. setting circle as you did the RA. circle, just leave it be if it was set as per the instructions in the top paragraph).  Do not worry too much about the Dec. of 45', as most Dec circles are marked only in degrees and not minutes(guesstimate the minutes as you see fit). 

                               The Green circles represent the reticle of a Telrad finder(0.5°, 2°, 4°).

Once you are satisfied that Delta Corvus is centred in your eyepiece (Delta has a small companion star to its side.  Make sure of the star's identity and co-ordinates as a mistake here negates the whole process to follow), and that the proper co-ordinates are set on the setting circles, you can now move the scope until the circles are reading the co-ordinates for M104 (RA.= 12:39.9 Dec. = -11° 37').  If you set up the circles properly, are close to polar alignment, and had centred your scope on the right bright star, you should now be looking at M104 or are very close to it.  Use a low powered eyepiece enough to see the object, but still give you a wide enough view in case you are off by a few degrees.  As long as your clock drive is running, you can continue to find objects near your bright star.  Two words of caution, if the clock drive stops you will have to reset your circles to the bright alignment star, and the farther away from the bright star you go the more inaccurate the setting circles will become.  For your next object, find another near by bright star of known co-ordinates and reset the setting circles as above.  With practice I have found that this procedure becomes fast and accurate.  Good hunting.