To complete Step 3 you will need Kphot. Kphot was written by Uwe Pilz and is available for free by clicking the following link, which will start the download automatically:http://kometen.fg-vds.de/kphotsoftware.zipI created a folder called c:\kphot and unzipped the field into that directory. There’s a useful help file (a readme text file) and Roger Dymock has also provided additional information on the BAA webpage referred to in Step 1.You will see from the help file that you will ned to download comet data and save as comets.dat in the base Kphot directory (c:\kphot in my case). This file is available for free from the following link:http://www.minorplanetcenter.net/iau/Ephemerides/Comets/SoftwareComets.htmlYou’ll need to download the “Guide (Project Pluto)” version as a text file, but note that you’ll need to change the file name from the default (Soft02Cmt.txt) to comets.dat as required by Kphot.Kphot uses the multibox text file produced by FoCAs in Step 2 (multi.txt). You’ll need to open the multi.txt file and save it as a new file called “kp.txt” in your Kphot directory, in my case:c:\kphot\kp.txtTo run Kphot you’ll need to open a dos programme window - hit the Windows icon, then All Programes > Accessories > Command PromptHere’s a shot showing what I see:Next change directory to your kphot root - in my case “cd:\kphot”Now you can run the Kphot command. Instructions are in the readme file that comes with Kphot but in my case it’s:kphot -m 1 -n 6 -T MC 40.6Y 9 -B HIL -g c:\kphot\comets.datFor speed I keep this string in a “post it” on my desktop and whenever I run Kphot I just have to change one number, the number in position 15 after “n”. This refers to the number of multibox estimates that were produced by FoCAs in Step 2. Recall that in the case of 70P FoCAs produced six multibox measurements (10x10, 20x20, 30x30, 40x40, 50x50 and 60x60) so I have put the number 6 into position 15 in the string above. But sometimes FoCAs produces less than six measurements. For example, if FoCAs produced only three measurements (10x10, 20x20 and 30x30) then I would put 3 into position 15 in the string above.In this case it’s 6, so put the string into the dos prompt and click return, as shown below:Kphot will run in an instant and amend the file kp.txt in the root directory of Kphot. Here’s a couple of screen shots showing the file before and after running Kphot in my case:You will see that Kphot has added a third line and the most important measurement, the visual equivalent magnitude, is at position 29 in the third line. In this case it’s magnitude 15.0.So to recap, we now have the following magnitude estimates.Six multibox estimates thanks to Astrometrica and FoCAs in Steps 1 and 2:Box size10x1020x2030x3040x4050x5060x60Magnitude16.6016.0015.6615.4515.3215.23MPC magnitude estimate of 16.6 thanks to Astrometrica and FoCAs in Steps 1 and 2 (the 10x10 estimate as set out above).Visual equivalent magnitude of 15.0 thanks to Kphot.That’s the end of Step 3.