My IPA was in the primary for 10 days and gravity readings where steady before racking to the secondary. It’s been in the secondary for 13 days now and emits one bubble every 75 seconds on average. Temps have been a few degrees lower than recommended since racking. Can I bottle this now?
If you got consistent hydrometer readings over several successive days then yes, go ahead and bottle. 3+ weeks in the fermenter sounds like more than sufficient time for your IPA.
By the way, the bubble rate is not an accurate way of measuring fermentation activity. Bubbles can be produced by changes in ambient temperature and by simply walking past your carboy/bucket!
I should rectify this post slightly. You should also check that your FG is reasonably close to what you expected. If it is way off (i.e. 1.03 when it should be 1.01) then you may have a "stuck fermentation" which could lead to problems with explosive bottles etc.
In summary, check that you are close to your target FG, check consistency of hydrometer readings over 3 successive days, and then bottle!
See also here.