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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"

906 results found.

  1. EP241103a: an X-ray transient detected by Einstein Probe
  2. EP241101a: BOOTES-7 optical upper limit
  3. EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
  4. EP241101a: EP-WXT detection of a fast X-ray transient
  5. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  6. EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
  7. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  8. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  9. EP241026b: EP-FXT follow-up observation
  10. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  11. EP241021a: ATCA radio observations
  12. GRB 241026A Fermi GBM Analysis
  13. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  14. EP241026b: EP detection of a fast X-ray transient
  15. GRB 241025A: Fermi GBM Observation
  16. EP 241021a: Swift-XRT observations
  17. EP241025a (GRB 241025A): EP observations update
  18. EP 241021A: Swift ToO observations
  19. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  20. EP241021a: EP-FXT follow-up observation update
  21. EP241021a: 1.3m DFOT Optical observations
  22. EP241021a: TRT optical observations
  23. EP241021a: NOT likely optical counterpart
  24. GRB 241018A: EP-FXT afterglow detection
  25. EP241021a: EP detection of a fast X-ray transient
  26. GRB 241001A: EP-FXT afterglow detection
  27. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  28. GRB 240930B: Fermi GBM Observation
  29. EP240930a: EP-FXT follow-up observation update
  30. EP240930a: EP-WXT detection of a fast X-ray transient
  31. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  32. EP240918b and EP240918c: EP-FXT follow-up observations
  33. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  34. EP240919a: EP-FXT follow-up observation update
  35. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  36. EP240919a is likely a GRB event
  37. EP240919a: EP-WXT detection of a fast X-ray transient
  38. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  39. EP240918a: EP observation update
  40. EP240918a: Swift-XRT observation
  41. EP240918a: YAHPT Optical Upper Limit
  42. EP240918a: Optical upper limits with Kinder observations
  43. EP240918a: an X-ray transient detected by Einstein Probe
  44. The EP-WXT triggers 01709047257 and 01709047278 are not real sources
  45. EP240913a: VLT/HAWK-I near-infrared upper limits
  46. GRB 240913C: Fermi GBM detection
  47. EP240913a: NOT optical upper limits
  48. EP240913a: JinShan optical upper limits
  49. EP240913a: A GRB Event
  50. EP240913a: EP-WXT detection of a fast X-ray transient
  51. EP240908a: Updates on the WXT detection result around the trigger time
  52. EP240908a: EP detection of a fast X-ray transient
  53. SVOM GRB 240821A: optical afterglow discovery
  54. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  55. EP240820a: PRIME J-band Observations
  56. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  57. EP240820a: EP detection of a fast X-ray transient
  58. EP240816a: PRIME upper limits
  59. GRB 240819A : an X-ray transient detected by SVOM/ECLAIRs
  60. GRB 240819A: X-ray follow-up observation with EP-FXT
  61. EP240816b: KAIT optical upper limit
  62. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  63. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  64. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  65. EP240807a: PRIME H-band upper limits
  66. X-ray Transient EP240807a: PRIME near-infrared upper limits
  67. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  68. EP240807a: STEP/T80S optical limits
  69. EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
  70. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  71. EP240802a/GRB240802A: KAIT optical upper limit
  72. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  73. EP240807a: EP-WXT detection of a fast X-ray transient
  74. EP240806a: KAIT optical observations
  75. EP240806a: LCOGT optical counterpart detection
  76. EP240806a: EP-FXT detection of the X-ray emission
  77. EP240806a: EP-WXT detection of a fast X-ray transient
  78. EP240804a: VLT/X-shooter spectroscopic redshift
  79. EP240804a: LCOGT optical counterpart detection
  80. EP-WXT trigger 00109017646 is not a real source
  81. EP240804a: NOT optical counterpart detection
  82. EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  83. EP240802a: correction of EP-WXT trigger time in GCN 37019
  84. EP240802a: Montarrenti Observatory optical upper limit
  85. EP240801a: Osservatorio Astronomico Nastro Verde upper limit
  86. EP240802A: Bassano Bresciano Observatory upper limit
  87. EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  88. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  89. EP240801a: Leavitt Observatory optical observations
  90. EP240801a: NOT optical observations
  91. EP240801a: follow-up observation with LCOGT
  92. EP240801a: GSP follow-up observations of the candidate counterpart
  93. EP240801a: KAIT optical counterpart observations
  94. EP240801a: TRT optical counterpart detection
  95. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  96. EP-WXT trigger 01709002661 is not a real source
  97. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  98. EP240708a: X-ray follow-up observations with Swift/XRT
  99. EP-WXT flaring star and the optical flaring activity during its decay phase
  100. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star

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