This form allows you to calculate HiPERCAM object counts, sky counts and signal-to-noise ratios on the WHT and GTC. The calculation is based on the measured HiPERCAM+GTC zero points for the u_s, g_s, r_s, i_s and z_s filters.

The following assumptions are made:

• Binning factors in x and y are always the same.
• The peak signal per pixel in a seeing disc is calculated assuming a two-dimensional Gaussian profile.
• The number of pixels covered by the seeing disc is calculated assuming an aperture of radius 1.5 times the seeing.
• Extinction and sky bightness values have been taken from the ING ETC: signal.
• The WHT counts are calculated by scaling the GTC values by the ratio of apertures (taking into account the central obstruction) and the extra reflection at the GTC (assumed to be 90% efficient).

If you don't know the SDSS magnitude of your target, you can use the formulae in Table 7 of Smith et al. (2002) to convert from UBVRI to ugriz magnitudes.