[Andrew C]

Hi Alistair,

I think for that you would need to customise the first spreadsheet workbook.

You will see towards the right side of the INT(ERESTING) OBJ(ECTS) sheet in this workbook a series of columns CR through DJ whose formulae are used to determine those objects in the full list that are visible in each quadrant and overhead at the nominated time and place (in the demo 9.30pm January 15th in Alice Springs). e.g. TUC47 is visible in the south at ALT 31, AZ 199.

If you were to change the LAT and LONG to Melbourne
(say -38/145) and the DISPLAY TIME UT to 11.00 (which = 22.00 EDST) on the LSTCALC sheet, TUC47 changes to ALT 45, AZ 202. You will also notice that some of the entries in the south display jan column (such as NGC 6397 at row 183) have changed from 0 to 1, indicating that this object is now visible where it wasn't before. Conversely, others have disappeared from view, such as NGC1316/1317 at row 33. In fact this latter one has disappeared upwards, and is now visible in the adjacent zenith column and chart.

For clarity in the demo, I had removed the formulae from the alt and az columns DA & DB for objects that are not visible or 'active' in the south at that time and place (and similarly for the other quadrants) but they are easily reintroduced by copying the az and alt formulae from an active object above or below (don't copy across).

If you are not interested in generating the charts, you can also change the formulae for example so that all quadrants are included in the one set of columns. If you look e.g. at the south SCP entry (cell CZ2) you will see that I am only setting this entry to active ("1") if the altitude is between 0 and 70 degrees, and the az is between 135 (southeast) and 225 (southwest). You could remove the az test altogether, and change the alt to accept the range 0-90, or say 20-90 if you want to exclude objects that are close to the horizon.

Note that e.g January 15th at a particular time is nearly equivalent to December 15th at the same time plus 2 hours, so you can use the chart for any date by adjusting the time. The columns AN to CP take account of the 'nearly' which I use for the other months charts, but you could skip worrying about using those if you are not looking for a precise altitude and azimuth.

For magnitudes you could add a further column, and introduce a magnitude test into the formula as well if you want to show only those above a certain brightness.

Cheers,

Andrew