HSpot is a huge and complex piece of software (more than 170 000 lines of Java code) that has seen constant increases in functionality and that has involved now around 30 Man-Years of development. It has gone through extensive testing on Windows, Mac, Linux and Solaris after every update. We believe that all of the major and many of the minor bugs that are under our control were located in these campaigns.

With Herschel in flight operations constant, small updates were made in the light of the in-flight performance of instruments (e.g. sensitivities and HIFI band widths, the last of these, a minor update in HIFI bands, was made as recently as February 2013), there have been numerous changes, some major, as AOTs were tested and refined in space and better ways were found of taking data than those initially envisaged on the ground and new, second generation observing modes were developed. The observing modes themselves have been quite stable since 2011, but further changes have been made, where indicated, after more detailed characterisation based on a larger quantity of in-flight calibration; these though have affected an increasingly small number of observations and, where necessary, the users have been contacted personally to notify them of the impact on their observations.

Where we are aware of a significant problem that has not been fixed, or an issue that the user should be aware of, it is listed below. Please note though that not all issues that are reported are under our direct control as HSpot also uses some external facilities and also some problems refer to parts of the code that are Spot Core and thus not maintained at the Herschel Science Centre.

As Herschel moved over to flight operations and HSpot was being used by astronomers in increasingly complex ways, particularly by the instrument specialists who are planning and carrying out observations on board who have been modifying and adapting, sometimes extensively, the way that observations are carried out, it is natural that the number of issues reported by users started to increase again initially. As a result, big changes were seen in HSpot in a short space of time during the first year and a half of the mission. Over the last two years the number of issues reported has declined rapidly again.

Please note that, in most cases, the average user will not even have been aware of these problems and their impact on normal HSpot use was small, if any. The typical problem that has been reported in this time has been a minor irritation to the average user and something that can be worked around, even if he or she has even been aware of it, rather than representing a serious issue for the astronomical community.

We are now entering a post-Operations phase for HSpot in which little or no maintenance will be carried out, after a phase in which manpower for maintenance has been run down progressively. This has required a close scrutiny of remaining issues in HSpot. In most cases, where there is a minor issue that has not caused significant problems to users it has been archived: these are features of HSpot that can be worked-around quite easily, or even ignored.

In a few cases important bugs have been identified that have appeared mainly due to a change in operating system, or in the underlying software (on occasion this has been due to a subtle change in some software external to HSpot that appears in no way related when the change has been made and has only manifested itself in software acceptance test campaigns), or a change in the configuration of an external server. High priority has been given to fixing these issues so that HSpot retains 100% functionality until no longer required for scheduling either in its standard Astronomer Mode, or in its specialist calibration mode that will still be used in the post-cryogen campaign of final tests of instruments and service module. Once these final post-cryogen observations are scheduled, HSpot will enter a final post-Operations state in which we can no longer guarantee that it will retain full functionality.

The known and potential issues that may remain are divided into HSpot issues and proposal handling issues. Within each, they are sub-divided into sections for ease of search.