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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').

15473 results found.

  1. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  2. EP240426b: AST3-2 optical upper limit
  3. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  4. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  5. EP240426b: EP-WXT detection of a new fast X-ray transient
  6. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  7. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  8. XMM-Newton observation of EP240426a
  9. GRB 240414A: NOEMA detection
  10. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  11. EP240426a: GMG optical upper limit
  12. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  13. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  14. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  15. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  16. GRB 240422A: Glowbug gamma-ray detection
  17. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  18. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  19. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  20. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  21. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  22. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  23. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  24. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  25. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  26. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  27. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  28. LIGO/Virgo/KAGRA S240422ed: LAST optical observations
  29. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  30. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  31. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  32. LXT240402A/GRB240402B: Chandra X-ray detection
  33. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  34. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  35. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  36. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  37. GRB 240421A: Glowbug gamma-ray detection
  38. GRB 240414A: radio detection with the VLA
  39. Fermi-LAT gamma-ray observations of IceCube-240419A
  40. GRB 240414A: AMI-LA radio observations
  41. GRB 240414A: LBT optical detection
  42. GRB 240419B : MITSuME Akeno optical upper limits
  43. GRB 240421B: AstroSat CZTI detection
  44. GRB240421B: Zadko Observations
  45. GRB 240421B: Fermi GBM Observation
  46. GRB 240421B: J-band upper limits from WINTER
  47. GRB 240421B: Swift/UVOT Upper Limits
  48. GRB 240421B: Enhanced Swift-XRT position
  49. EP240417a: no counterpart detection by SOAR
  50. EP240420a: Xinglong decaying optical counterpart
  51. GRB 240421B: Swift detection of a burst
  52. EP240420a: Nanshan optical counterpart observations
  53. EP240420a: GWAC-F50A optical upper limit
  54. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  55. EP240420a: NOT optical counterpart candidate and potential host
  56. Fermi trigger No 735280430: Global MASTER-Net observations report
  57. GRB240419A: Skynet Optical Afterglow Analysis
  58. GRB240418A - Candidate afterglow from NIRES
  59. GRB 240419B: Swift/UVOT Upper Limits
  60. EP240420a: EP-WXT detection of a fast X-ray transient
  61. GRB 240419A: Swift/UVOT Upper Limits
  62. GRB 240419B: optical afterglow from the NOT
  63. GRB 240419B: Enhanced Swift-XRT position
  64. GRB 240418A: Swift/UVOT Upper Limits
  65. GRB 240419A: REM NIR afterglow detection
  66. GRB 240418A: Swift-XRT refined Analysis
  67. GRB 240419B: Swift detection of a burst
  68. GRB 240411B: Swift/UVOT Detection
  69. GRB 240419A: VLT optical afterglow detection
  70. GRB 240419A: Enhanced Swift-XRT position
  71. EP240416a: J-band observations with WINTER
  72. EP240414a: GMG observation
  73. GRB 240419A: Swift detection of a burst
  74. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  75. GRB 240418A: NOT optical upper limits
  76. GRB 240418A: Enhanced Swift-XRT position
  77. GRB 240418A: AKO Upper Limit
  78. GRB 240418A: Swift detection of a burst
  79. EP240417a: EP-WXT detection of a fast X-ray transient
  80. LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
  81. GRB 240415A: Glowbug gamma-ray detection
  82. GRB 240414A: Glowbug gamma-ray detection
  83. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  84. EP 240416a: Xinglong and NOT decaying optical counterpart
  85. GRB 240411A: Glowbug gamma-ray detection
  86. EP240416a: Kinder optical counterpart candidate
  87. EP240416a: EP-WXT detection of a fast X-ray transient
  88. GRB 240414A: AbAO optical upprer limit
  89. GRB 240415A: Swift/UVOT Detection
  90. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  91. GRB 240415A: Earliest optical followup with the Kinder observations
  92. GRB 240414A: GMG observation
  93. EP240414a: EP-FXT follow-up observation
  94. GRB 240415A: Enhanced Swift-XRT position
  95. GRB 240415B: Swift ToO observations
  96. GRB 240415A: OHP/T193 optical observations
  97. GRB 240415A: SAO RAS optical observations
  98. GRB 240415A: Mondy optical transient detection
  99. GRB 240414A: Photometric observation from 2.2m CAHA
  100. GRB 240414A: Swift/UVOT Detection

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