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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

1096 results found.

  1. EP241021a: ATCA radio observations
  2. GRB 241026A Fermi GBM Analysis
  3. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  4. EP241026b: EP detection of a fast X-ray transient
  5. GRB 241025A: Fermi GBM Observation
  6. EP 241021a: Swift-XRT observations
  7. EP241025a (GRB 241025A): EP observations update
  8. EP 241021A: Swift ToO observations
  9. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  10. EP241021a: EP-FXT follow-up observation update
  11. EP241021a: 1.3m DFOT Optical observations
  12. EP241021a: TRT optical observations
  13. EP241021a: NOT likely optical counterpart
  14. GRB 241018A: EP-FXT afterglow detection
  15. EP241021a: EP detection of a fast X-ray transient
  16. GRB 241001A: EP-FXT afterglow detection
  17. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  18. GRB 240930B: Fermi GBM Observation
  19. EP240930a: EP-FXT follow-up observation update
  20. EP240930a: EP-WXT detection of a fast X-ray transient
  21. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  22. EP240918b and EP240918c: EP-FXT follow-up observations
  23. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  24. EP240919a: EP-FXT follow-up observation update
  25. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  26. EP240919a is likely a GRB event
  27. EP240919a: EP-WXT detection of a fast X-ray transient
  28. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  29. EP240918a: EP observation update
  30. EP240918a: Swift-XRT observation
  31. EP240918a: YAHPT Optical Upper Limit
  32. EP240918a: Optical upper limits with Kinder observations
  33. EP240918a: an X-ray transient detected by Einstein Probe
  34. The EP-WXT triggers 01709047257 and 01709047278 are not real sources
  35. EP240913a: VLT/HAWK-I near-infrared upper limits
  36. GRB 240913C: Fermi GBM detection
  37. EP240913a: NOT optical upper limits
  38. EP240913a: JinShan optical upper limits
  39. EP240913a: A GRB Event
  40. EP240913a: EP-WXT detection of a fast X-ray transient
  41. EP240908a: Updates on the WXT detection result around the trigger time
  42. EP240908a: EP detection of a fast X-ray transient
  43. SVOM GRB 240821A: optical afterglow discovery
  44. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  45. EP240820a: PRIME J-band Observations
  46. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  47. EP240820a: EP detection of a fast X-ray transient
  48. EP240816a: PRIME upper limits
  49. GRB 240819A : an X-ray transient detected by SVOM/ECLAIRs
  50. GRB 240819A: X-ray follow-up observation with EP-FXT
  51. EP240816b: KAIT optical upper limit
  52. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  53. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  54. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  55. EP240807a: PRIME H-band upper limits
  56. X-ray Transient EP240807a: PRIME near-infrared upper limits
  57. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  58. EP240807a: STEP/T80S optical limits
  59. EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
  60. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  61. EP240802a/GRB240802A: KAIT optical upper limit
  62. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  63. EP240807a: EP-WXT detection of a fast X-ray transient
  64. EP240806a: KAIT optical observations
  65. EP240806a: LCOGT optical counterpart detection
  66. EP240806a: EP-FXT detection of the X-ray emission
  67. EP240806a: EP-WXT detection of a fast X-ray transient
  68. EP240804a: VLT/X-shooter spectroscopic redshift
  69. EP240804a: LCOGT optical counterpart detection
  70. EP-WXT trigger 00109017646 is not a real source
  71. EP240804a: NOT optical counterpart detection
  72. EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  73. EP240802a: correction of EP-WXT trigger time in GCN 37019
  74. EP240802a: Montarrenti Observatory optical upper limit
  75. EP240801a: Osservatorio Astronomico Nastro Verde upper limit
  76. EP240802A: Bassano Bresciano Observatory upper limit
  77. EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  78. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  79. EP240801a: Leavitt Observatory optical observations
  80. EP240801a: NOT optical observations
  81. EP240801a: follow-up observation with LCOGT
  82. EP240801a: GSP follow-up observations of the candidate counterpart
  83. EP240801a: KAIT optical counterpart observations
  84. EP240801a: TRT optical counterpart detection
  85. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  86. EP-WXT trigger 01709002661 is not a real source
  87. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  88. EP240708a: X-ray follow-up observations with Swift/XRT
  89. EP-WXT flaring star and the optical flaring activity during its decay phase
  90. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  91. The EP-WXT source triggered on July 14th is likely a flaring star
  92. GRB240713A: X-ray follow-up observation with EP-FXT
  93. EP240708a: GSP optical upper limit
  94. EP240708a: KAIT optical upper limit
  95. EP240708a: SVOM/C-GFT optical upper limit
  96. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  97. EP240708a: EP-WXT detection of a fast X-ray transient
  98. EP240703b: GSP optical upper limit
  99. EP240703a and EP240703b: Swift/XRT upper limits
  100. EP240703a: KAIT optical upper limit

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