177P was originally discovered by E.E. Barnard using a 16cm refractor on 24 June 1889 and followed for about 6 weeks. Orbital solutions with the few positions available indicated that it had an intermediate period, likely to be in the range 128 -145 years and so would be due back in the Sun's vicinity early in the 21st century. 

On 23 June 2006, one day short of 117 years after Barnard's discovery, the LINEAR survey reported a newly discovered 17th magnitude object at a declination of -27° moving at 2.5"/min, but travelling almost due north. It was put on the NEO Confirmation page later that day and within hours, Luca Buzzi from Schiaparelli Observatory in Italy was first to report that this new object was cometary in appearance, noting that the object showed a 6" circular coma with a strong central condensation in images taken with a 0.60-m reflector.

Dan Green at the Central Bureau for Astronomical Telegrams (CBAT) quickly realised that the LINEAR discovery was in fact Barnard's comet returning and CBET 558 (subscription required) was issued on 24 June, followed by IAUC 8726 (subscription required) on 26 June 2006 with the recovery details.

The comet was picked up in 2006 on its way in to perihelion which was due on 28 August 2006. This would be a very favourable appearance, passing just 0.366 AU from the Earth on 19 July 2006 (see image above) and the comet was probably bright enough to be observed for 1-2 months before LINEAR found it, but at a southerly declination (-45°) that would have stopped the predominantly northern based NEO surveys such as LINEAR from picking it up much before June.

The following image (to the same scale and field size as the image on 2006 July 18th) was taken a week before perihelion, with the comet receding from the Earth. Even though the exposure was slightly shorter than the previous image the coma appears to be somewhat brighter, however, the brightness of the central condensation was measured to be essentially the same, at mag +15.7. A tail within the coma can be seen pointing in the anti-solar direction, but in the July 18th image this is only hinted at as a slight brightening to the southeast of the nuclear condensation.