2013 EV9 was discovered by the Spacewatch survey on images taken by T. H. Bressi with the Spacewatch 0.90-m f/3 reflector (+ CCD mosaic) on 2013, Mar. 2. Its Tj parameter is 2.77, so it was a good T3 candidate.
Hidetaka Sato remotely observed it on 2013 Apr. 28.42 using a 0.51-m f/4.5 reflector from iTelescope, Siding Spring (MPC Q62), finding a softer aspect respect to stars (FWHM 4.8″ vs 3.6″-3.8″) and a small coma on a stack of 10 x 60 seconds images. On the following night (Apr. 29.16) he observed it again remotely with the same instrumentation but located near Mayhill (MPC H06), finding the FWHM to be 4.0″ respect to 3.3″ for the stars, with a compact coma 6-8″ wide in a stack of 10 x 60 seconds. Following his alert to the T3 mailing-list, I asked for some confirmations, which came as following.
Tomas Vorobjov observed it on two nights (Apr. 29.17-21 and Apr. 30.17-27) using the 1.3-m f/13 Western Kentucky University reflector at Kitt Peak. On the first night, stacking 18 x 120 seconds images, he found a coma 5″ across and a hint of tail in PA 120 degrees. On the second night, a stack of 54 x 120 seconds reveals a coma 5″ x 5″ and a tail 15″ long in PA 120 degrees.
Bill Ryan, Magdalena Ridge Observatory, obtained a set of images with the 2.4-m f/8.9 reflector on May 01.21. A stack of 4 x 60 seconds images measured by L. Buzzi, S. Foglia and himself shows a FWHM 50% larger than stars nearby (2.8″ vs 1.8″) with a coma 10″ wide, clearly extended to the south-east.
A stack of 31 x 75 seconds images obtained on May 01.12-14 by R. Holmes, Astronomical Research Institute, with a 0.76-m f/4 astrograph, and measured by L. Buzzi, S. Foglia and T. Vorobjov shows clearly a softer aspect respect to stars, with a 15″ coma elongated to the south-east.
Americo Watkins obtained remotely a set of images with the Mt.Lemmon 0.81-m f/7 reflector as part of the Sierra Stars Observatory Network, on Apr. 30.13-14. A stack of 8 x 60 seconds images measured by himself and L. Buzzi shows a 6″ x 5″ coma extended to the east.
CBAT released CBET 3503 (subscription required) on May 2; all the observations can be found on MPEC 2013-J10.
This is the first image of the discovery, made by Hidetaka Sato using iTelescope:

T. Vorobjov’s image from Kitt Peak:

W.H. Ryan image and FWHM profiles from MRO:

R. Holmes profiles from his 0.76-m f/4 – ARI:

A. Watkins’s image and profiles from Mt.Lemmon SkyCenter – SSON: