Herschel_Sprint

Most of Herschel's deep sky object work was done with his large 20 foot telescope completed in 1783.  Herschel would dictate his observations to his sister Caroline who sat inside the house and listened through an open window.  The scope had a focal length of twenty feet, an tilted 18.7" mirror, and was what we now call a "Herschelian" telescope having no secondary.   He generally used an eyepiece that gave a magnification of 157x and 15' 4" field of view.  The mirror was made of speculum, an alloy of two-thirds copper, one-third tin, and a small amount of arsenic.  Unlike the high quality mirrors of today, his speculum mirror was only 68% reflective, tarnished rapidly and required frequent repolishing.  The scope apparently had multiple mirrors that were frequently swapped to prevent down time.   Looking at the picture of the telescope you'll realize how large it was.  Rather than track it was a transit instrument, it pointed north-south along the meridian and observations were done by letting the objects drift through the field.  Ropes would allow a helper to raise and lower the telescope a few degrees as necessary during each sweep it increase the amount of sky scanned.

Hershel eventually made an even larger 40 foot telescope, but he preferred his large 20 because it had a better mirror and was easier to use.

Herschel Hustle Observing Program:

Herschel observed almost every clear night that English weather would allow.  The night of April 11, 1785 proved to be very special.  That night he pointed his telescope at Leo Minor and Coma Berenices.  Little did he know that in the next six hours he would be the first to see seventy-four galaxies.  For reference sake, that is more galaxies than any other discoverer had or has ever done visually during a single night.  It was done by letting the Earth's normal rotation cause the galaxies to drift through the field with minor 1-2 degree altitude corrections. He measured the coordinates and Caroline logged it all.

This observing program challenges you to recreate Herschel's efforts.  It will take a dark sky and big scope, but no fancy electronics, equipment, or superhuman efforts.  It is best preformed on a moonless night in April since that is when the objects cross the meridian in evening darkness and hopefully moderate temperatures.  The program is somewhat like a Messier Marathon in that a large number of objects are to be seen in a short time, but it has an historical basis and requires very little star hopping. 

Your task is to see as many of the galaxies that Herschel discovered on April 11, 1785 as possible.  When you attempt the Hustle and your chosen location may limit your options.  If you attempt it before April of any year you may be able to simply align your scope north-south and use an angle gauge to adjust the altitude of your scope to match the first object in the list.  At that point it becomes a waiting game until it and others drift into view.  Unfortunately, the first object is also the dimmest at magnitude 14.7.  You may wish to GoTo this first object or star hop to 23 LMi and work from there.  If you attempt it much after April the objects may be west of the meridian and you'll need to plan accordingly to see them all.

The Hustle should last for up to six hours.  The first seventy two on the list should take about four hours, but the last two galaxies are very far from the rest.  While we are trying to recreate Herschel's experience we do have the advantages of technology help us know where our telescope is pointed.  Missing a single galaxy might throw off the Hustle (do you need to move north or south to pick up the next galaxy?).  Use your technology advantage to keep track of where your are and where you are pointed.  This is particularly true if your aperture is on the small end or transparency is questionable.

If you are up for another challenge besides seeing seventy-four objects in one night, consider logging the time the object crosses the meridian and the altitude.  Armed with that information you should be able to calculate the actual Right Ascension and Declination of each galaxy.  Of course you might need a Caroline along with you to do the actual recording.

The table below shows a breakdown of the objects in terms of magnitude: