Question: What was launched first, The Wide Field Infrared Explorer or The Orbiting Astronomical Observatory 2?
Context: The Infrared Science Archive (IRSA) curates the science products of NASA's infrared and submillimeter projects, such as the Spitzer Space Telescope, the Wide-field Infrared Survey Explorer (WISE), the Infrared Astronomical Satellite (IRAS), and the Two Micron All-Sky Survey (2MASS).  IRSA also serves data from infrared and submillimeter European Space Agency missions with NASA participation, including the Infrared Space Observatory (ISO), Planck, and the Herschel Space Observatory.  s of 2014 , IRSA provides access to more than 20 billion astronomical measurements, including all-sky coverage in 20 bands, spanning wavelengths from 1 micron to 10 millimeters.  Approximately 10% of all refereed astronomical journal articles cite data sets curated by IRSA. The Orbiting Astronomical Observatory (OAO) satellites were a series of four American space observatories launched by NASA between 1966 and 1972, which provided the first high-quality observations of many objects in ultraviolet light.  Although two OAO missions were failures, the success of the other two increased awareness within the astronomical community of the benefits of space-based observations, and led to the instigation of the Hubble Space Telescope. Tod R. Lauer (born 1957) is an American astronomer on the research staff of the National Optical Astronomy Observatory.  He was a member of the Hubble Space Telescope Wide Field and Planetary Camera team, and is a founding member of the Nuker Team.  His research interests includes observational searches for massive black holes in the centers of galaxies, the structure of elliptical galaxies, stellar populations, large-scale structure of the universe, and astronomical image processing.  He was the Principal Investigator of the Destiny JDEM concept study, one of the precursors to the Wide Field Infrared Survey Telescope mission.  Asteroid 3135 Lauer is named for him.  He appears in an episode of the documentary series Naked Science.  He joined the New Horizons Pluto team in order to apply his extensive experience with deep space imaging to the New Horizons data, yielding significantly clearer and mathematically accurate images of Pluto and Charon. Meyer–Womble Observatory (MWO) is an astronomical observatory owned and operated by the University of Denver.  It is located near the summit of Mount Evans in the Arapaho National Forest approximately 60 km west of Denver, Colorado (USA).  At an elevation of 4326 m , it is the third-highest optical/infrared observatory in the world, and was the highest until the Indian Astronomical Observatory opened in 2001. Rozhen Observatory (Bulgarian: Национална астрономическа обсерватория - Рожен , "НАО-Рожен"; English: National Astronomical Observatory - Rozhen , "NAO-Rozhen"), also known as the Bulgarian National Astronomical Observatory, is an astronomical observatory, located in the Smolyan Province, 90 kilometers south of the city of Plovdiv, Bulgaria.  The nearest town, Chepelare, is 15 kilometers away.  The observatory is owned and operated by the Institute of Astronomy of the Bulgarian Academy of Sciences (BAS).  It was officially opened on 13 March 1981, almost 20 years after Bogomil Kovachev – a professor of astronomy at BAS, known as its founder – had started working towards that goal.  The Observatory is the largest in Southeastern Europe and has an active team of about 50 astronomers.  It is the principal center for astronomical research in Bulgaria.  The minor planet 6267 Rozhen, was discovered at, and named after the observatory. The Wide Field Infrared Survey Telescope (WFIRST) is a future infrared space observatory that was recommended in 2010 by United States National Research Council Decadal Survey committee as the top priority for the next decade of astronomy.  On February 17, 2016, WFIRST was formally designated as a mission by NASA. The Wide Field Infrared Explorer (WIRE) was a satellite launched on March 5, 1999, on the Pegasus XL rocket into polar orbit between 409 and above the Earth's surface.  WIRE was intended to be a four-month infrared survey of the entire sky at 21-27 micrometres and 9-15 micrometres, specifically focusing on starburst galaxies and luminous protogalaxies. The Orbiting Carbon Observatory (OCO) is a NASA satellite mission intended to provide global space-based observations of atmospheric carbon dioxide (CO).  The original spacecraft was lost in a launch failure on 24 February 2009, when the payload fairing of the Taurus rocket which was carrying it failed to separate during ascent.  The added mass of the fairing prevented the satellite from reaching orbit.  It subsequently re-entered the atmosphere and crashed into the Indian Ocean near Antarctica.  The replacement satellite, Orbiting Carbon Observatory 2, was launched 2 July 2014 aboard a Delta II rocket.  The Orbiting Carbon Observatory 3, a stand-alone payload built from the spare OCO-2 flight instrument, will be installed on the International Space Station's Kibō Exposed Facility in December 2016. Vilnius University Astronomical Observatory is an astronomical observatory of Vilnius University.  It was founded on 1753 by initiative of Thomas Zebrowski.  The observatory is the fourth oldest observatory in the Europe.  While the observatory is no longer able to make astronomical observations due to light pollution in Vilnius (observations are carried out at Molėtai Astronomical Observatory), it continues scientific research. The Orbiting Astronomical Observatory 2 (OAO-2, nicknamed Stargazer) was a space observatory launched on December 7, 1968.
Answer: The Orbiting Astronomical Observatory 2