UPDATE: "Halloween pumpkin" video and images from Calar Alto
Videos of the "Halloween pumpkin"
First image is a a 20-s exposure with the autoguider camera of the PMAS spectrograph on the 3.5-m telescope. 2015TB145 is visible as a point-like source in the bottom-left corner.
Note the telescope was following the quick motion of the object, thus stars in the field appear as trails (two are visible near the central "blind hole" corresponding to the spectrograph fibres).
The second image corresponds to a spectrum of 2015TB145, probably the unique one obtained with a multi-fibre spectrograph! Tens of spectra are actually visible (corresponding to the nearly horizontal lines, wavelength from ca. 3500 A to 4000 A from left to right) but most correspond to empty sky, while the object falls on a few fibres of the spectrograph.