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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"

929 results found.

  1. EP250223a: Einstein Probe detection of an X-ray transient
  2. EP250220a: EP-FXT follow-up observations
  3. EP250220a: EP-WXT detection of a fast X-ray transient
  4. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  5. The EP-WXT trigger 01709131775 is likely a flaring star
  6. GRB 250215A / EP250215a: LCO detection of the afterglow
  7. GRB 250215A: Swift/UVOT Upper Limits
  8. GRB 250215A: Swift-XRT refined Analysis
  9. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  10. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  11. EP250207b: VLA radio upper limits
  12. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  13. EP250207b: Liverpool Telescope possible optical counterpart
  14. EP250207b: Gemini GMOS-N z-band observations
  15. EP250207b: a new X-ray transient detected by Einstein Probe
  16. EP250207a: EP-WXT detection and XRT follow-up observation
  17. The EP-WXT trigger 01709131347 is likely a flaring star
  18. The EP-WXT trigger 01709131332 is likely a flaring star
  19. The EP-WXT trigger 01709131290 is likely a flaring star
  20. GRB 250205A: REM NIR upper limit
  21. EP250205a/GRB 250205A: correction to the source localization
  22. EP250205a/GRB 250205A: Einstein Probe observation
  23. The EP-WXT trigger 01709131196 is likely a flaring star
  24. The EP-WXT trigger 01709131153 is not a real source
  25. EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
  26. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  27. The EP-WXT trigger 01709131085 is likely a flaring star
  28. GRB 250127A: Swift-XRT observations
  29. GRB 250127A: EP-FXT afterglow detection
  30. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  31. EP250125a: REM optical counterpart detection
  32. EP250125a: Swift/XRT detection of a fading counterpart
  33. EP250125a: a new X-ray transient detected by Einstein Probe
  34. The EP-WXT trigger 01709130758 is a false trigger
  35. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  36. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  37. EP 250108A: Late-time optical observation by LCO
  38. EP250111a: Swift/XRT detection and fading
  39. EP250111a: NOT likely optical counterpart
  40. EP250111a: a new X-ray transient detected by Einstein Probe
  41. EP250108a: further NOT optical observations
  42. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  43. EP250108a: EP-FXT follow-up observation
  44. The EP-WXT trigger 01709130111 is likely a flaring star
  45. EP250109a: Swift/UVOT non-detection
  46. EP250108a: Liverpool Telescope likely optical counterpart
  47. EP250109a: Swift/XRT non-detection
  48. EP250109a: EP-WXT detection of an X-ray transient
  49. EP250108a: EP-WXT detection of an X-ray transient
  50. The EP-WXT trigger 01709129925 is likely a flaring star
  51. GRB 241229A: SVOM/VT optical upperlimit
  52. EP241231b: optical upper limit with the Liverpool Telescope
  53. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  54. EP241217a: VLA Radio Detection

  55. GRB 241229A: EP-FXT X-ray afterglow confirmation
  56. GRB 241229A: Swift-XRT observations
  57. GRB 241229A: EP-FXT afterglow candidates
  58. EP240702a: 7DT Optical upper limits
  59. EP241223a: EP-WXT detection of a fast X-ray transient
  60. The EP-WXT trigger 01709129287 is likely a flaring star
  61. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  62. EP241217a: optical upper limit with the Liverpool Telescope
  63. GRB 241209B: EP-FXT afterglow detection
  64. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  65. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  66. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  67. GRB 241217A / EP241217b: NOT optical upper limits
  68. EP241217a: NOT optical observations
  69. EP241119a: 7DT Optical upper limits
  70. GRB 241209A: ATCA radio follow-up observations
  71. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  72. EP241217a: Swift-XRT Detection
  73. EP241217a: EP detection of an X-ray transient
  74. The EP-WXT trigger 01709129023 is likely a flaring star
  75. The EP-WXT trigger 01709128948 is likely a flaring star
  76. The EP-WXT trigger 01709128921 is likely a flaring star
  77. EP trigger ID 01709128824 is not a real source
  78. EP 241208A : Detection of a long soft transient by SVOM/ECLAIRs
  79. EP241213a/GRB241213a: Likely joint detection and INTEGRAL/SPI-ACS counterpart
  80. EP241213a: EP detection of An X-ray Transient
  81. GRB 241209A: EP-FXT follow-up observations
  82. EP241208a: EP-FXT follow-up observations
  83. EP241206a: 1.5m OSN optical limit
  84. EP241208a: EP detection of a fast X-ray transient
  85. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  86. EP241206a: BOOTES Global Network optical limits
  87. EP241206a: EP detection of a fast X-ray transient
  88. EP241201a: EP-FXT follow-up observations
  89. EP241201a: BOOTES-5 optical upper limit
  90. EP241202b: EP detection of a fast X-ray transient
  91. EP241201a: EP detection of a fast X-ray transient
  92. The EP-WXT trigger 01709126243 is not a real source
  93. The EP-WXT trigger 01709125191 is not a real source
  94. EP241126a: WFST Observations
  95. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  96. EP241126a: EP-FXT follow-up observation update
  97. EP241126a: GSP detects optical counterpart
  98. EP241126a: TRT optical counterpart detection
  99. EP241126a: EP detection of a fast X-ray transient
  100. GRB 241113B: EP-FXT afterglow detection

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