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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"

905 results found.

  1. EP241101a: BOOTES-7 optical upper limit
  2. EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
  3. EP241101a: EP-WXT detection of a fast X-ray transient
  4. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  5. EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
  6. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  7. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  8. EP241026b: EP-FXT follow-up observation
  9. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  10. EP241021a: ATCA radio observations
  11. GRB 241026A Fermi GBM Analysis
  12. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  13. EP241026b: EP detection of a fast X-ray transient
  14. GRB 241025A: Fermi GBM Observation
  15. EP 241021a: Swift-XRT observations
  16. EP241025a (GRB 241025A): EP observations update
  17. EP 241021A: Swift ToO observations
  18. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  19. EP241021a: EP-FXT follow-up observation update
  20. EP241021a: 1.3m DFOT Optical observations
  21. EP241021a: TRT optical observations
  22. EP241021a: NOT likely optical counterpart
  23. GRB 241018A: EP-FXT afterglow detection
  24. EP241021a: EP detection of a fast X-ray transient
  25. GRB 241001A: EP-FXT afterglow detection
  26. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  27. GRB 240930B: Fermi GBM Observation
  28. EP240930a: EP-FXT follow-up observation update
  29. EP240930a: EP-WXT detection of a fast X-ray transient
  30. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  31. EP240918b and EP240918c: EP-FXT follow-up observations
  32. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  33. EP240919a: EP-FXT follow-up observation update
  34. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  35. EP240919a is likely a GRB event
  36. EP240919a: EP-WXT detection of a fast X-ray transient
  37. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  38. EP240918a: EP observation update
  39. EP240918a: Swift-XRT observation
  40. EP240918a: YAHPT Optical Upper Limit
  41. EP240918a: Optical upper limits with Kinder observations
  42. EP240918a: an X-ray transient detected by Einstein Probe
  43. The EP-WXT triggers 01709047257 and 01709047278 are not real sources
  44. EP240913a: VLT/HAWK-I near-infrared upper limits
  45. GRB 240913C: Fermi GBM detection
  46. EP240913a: NOT optical upper limits
  47. EP240913a: JinShan optical upper limits
  48. EP240913a: A GRB Event
  49. EP240913a: EP-WXT detection of a fast X-ray transient
  50. EP240908a: Updates on the WXT detection result around the trigger time
  51. EP240908a: EP detection of a fast X-ray transient
  52. SVOM GRB 240821A: optical afterglow discovery
  53. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  54. EP240820a: PRIME J-band Observations
  55. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  56. EP240820a: EP detection of a fast X-ray transient
  57. EP240816a: PRIME upper limits
  58. GRB 240819A : an X-ray transient detected by SVOM/ECLAIRs
  59. GRB 240819A: X-ray follow-up observation with EP-FXT
  60. EP240816b: KAIT optical upper limit
  61. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  62. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  63. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  64. EP240807a: PRIME H-band upper limits
  65. X-ray Transient EP240807a: PRIME near-infrared upper limits
  66. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  67. EP240807a: STEP/T80S optical limits
  68. EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
  69. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  70. EP240802a/GRB240802A: KAIT optical upper limit
  71. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  72. EP240807a: EP-WXT detection of a fast X-ray transient
  73. EP240806a: KAIT optical observations
  74. EP240806a: LCOGT optical counterpart detection
  75. EP240806a: EP-FXT detection of the X-ray emission
  76. EP240806a: EP-WXT detection of a fast X-ray transient
  77. EP240804a: VLT/X-shooter spectroscopic redshift
  78. EP240804a: LCOGT optical counterpart detection
  79. EP-WXT trigger 00109017646 is not a real source
  80. EP240804a: NOT optical counterpart detection
  81. EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  82. EP240802a: correction of EP-WXT trigger time in GCN 37019
  83. EP240802a: Montarrenti Observatory optical upper limit
  84. EP240801a: Osservatorio Astronomico Nastro Verde upper limit
  85. EP240802A: Bassano Bresciano Observatory upper limit
  86. EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  87. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  88. EP240801a: Leavitt Observatory optical observations
  89. EP240801a: NOT optical observations
  90. EP240801a: follow-up observation with LCOGT
  91. EP240801a: GSP follow-up observations of the candidate counterpart
  92. EP240801a: KAIT optical counterpart observations
  93. EP240801a: TRT optical counterpart detection
  94. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  95. EP-WXT trigger 01709002661 is not a real source
  96. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  97. EP240708a: X-ray follow-up observations with Swift/XRT
  98. EP-WXT flaring star and the optical flaring activity during its decay phase
  99. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  100. The EP-WXT source triggered on July 14th is likely a flaring star

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